DE69714387T2 - Silver halide color photographic light-sensitive material and method of forming a color image - Google Patents

Abstract

The present invention provides a silver halide color photographic light-sensitive material comprising a substrate having a photographic constituent layer coated thereon including at least one light-sensitive layer which comprises a light-sensitive silver halide emulsion, a developing agent, a compound capable of forming a dye by a coupling reaction with the oxidation product of the developing agent, and a binder, the silver halide color photographic light-sensitive material after the exposure thereof being put together with a processing material comprising a substrate having a constituent layer coated thereon including a processing layer comprising a base and/or a base precursor, in the presence of water supplied to the light-sensitive layer of the silver halide color photographic light-sensitive material or to the processing layer of the processing material in an amount ranging from 1/10 to the equivalent of an amount which is required for the maximum swelling of the entire coating layers of these materials, so that the light-sensitive layer and the processing layer face each other, and being heated for the purpose of heat development to form a color image in the silver halide color photographic light-sensitive material, in which the light-sensitive silver halide emulsion contains at least one ion selected from the group consisting of a metal ion and a metal complex ion which are each an electron trap having a depth of 0.6 eV or less, and contains at least one kind of tabular grain having an average aspect ratio ranging from 4 to 100. The silver halide color photographic light-sensitive material of the present invention has a high sensitivity and is well suited to image formation by a simple and rapid process which has very few adverse affects on the environment.

Description

BACKGROUND OF THE INVENTION Field of the invention

The present invention relates to a silver halide color photographic light-sensitive material and a method for forming images using this light-sensitive material.

Description of the state of the art

Due to a remarkable development of photosensitive materials for color photography and use of silver halides, high-quality color images are now readily available. For example, according to ordinary color photography, a color print is obtained by the process comprising taking a photographic image using a color negative film, developing the film, printing the image information recorded on the color negative film optically on color photographic paper. Recently, this process has made remarkable progress and large-scale color development laboratories in which a large quantity of color prints are produced in a very efficient manner have spread in stores, together with so-called mini-laboratories which are small in size and have simple image-making processing devices. Therefore, anyone can easily make use of color photography.

Color photography, which is now in common use, reproduces color by the subtractive color process. Generally, a negative color film comprises a permeable support and light-sensitive layers disposed thereon which use a silver halide emulsion as a light-sensitive component having sensitivity to the blue, green and red wavelength range of light, and a so-called color coupler used to produce a yellow, magenta or cyan dye as a complementary color tone to the sensitive wavelength range. of the layer, and thereby a colored image can be formed by the combination of the above photosensitive layer capable of forming a dye. A color negative film which has been imagewise exposed in taking a photograph is developed in a color developer containing a primary amine developing agent. In this process, the developing agent develops, i.e., reduces the exposed silver halide grains, and the oxidation product of the developing agent, which is formed simultaneously with the above reduction, undergoes a coupling reaction with the color coupler to form a dye. The silver produced by the color development (developed silver) and the unreacted (unexposed) silver halide are removed by means of a bleaching process and a fixing process. This forms a colored image on the color negative film. Consequently, a color photographic paper comprising a reflective support and photosensitive layers formed thereon having the same combinations of the photosensitive wavelength range and the color tone to be produced as in the color negative film is subjected to exposure through the developed negative film and color developing, bleaching and fixing processes in the same manner as in the case of the negative film, thereby obtaining a color print having a color image reproducing an original image thereon.

Although these color print producing systems are now widely adopted, there is a growing demand for a simple system. The first reason is that skill and craftsmanship are necessary because of the need for precise control of the composition and temperature of the processing solution in a processing bath for the above-mentioned process consisting of color development, bleaching and fixing. The second reason is that a closed device exclusively for use in the development process is often required due to substances contained in the processing solution such as a developing agent and an iron chelate compound as a bleaching agent, the discharge of which is regulated from the viewpoint of environmental protection. The third reason is that the currently available system does not fully meet the requirement for rapid image reproduction because the above-mentioned development process still requires a long time, although the time has been shortened by recent progress in technology.

Against this background, there has been a strong demand for a simpler and faster system which does not use the developing agent and bleaching agent currently in use for a conventional color image forming system and which thus minimizes the adverse impact on the environment.

To meet the above requirements, many improved techniques have been proposed in recent years. For example, IS & T's 48th Annual Conference Proceedings, page 180 describes a system in which the dye formed in the development reaction is transferred to a mordant layer and then a light-sensitive material containing developed silver and unreacted silver halide is stripped from an image-receiving material carrying the mordant layer to separate the developed silver and unreacted silver halide from an image formed by the dye without using a bleach-fixing bath which has been indispensable in a conventional photographic process. However, this proposed technique cannot completely solve the environmental problems because it still requires a development process using a processing bath containing a developing agent.

Fuji Photo Co. Ltd. has proposed a Pictrography Color System which eliminates the need for a processing solution containing a developing agent. In the Pictrography Color System, a dye formed by a development reaction is fixed in a dye fixing layer, and the fixed dye in the layer is observed. In the Pictrography Color System, a small amount of water is supplied to a photosensitive material containing a base precursor which reacts with water to form a base. The photosensitive material and an image-receiving material are placed face to face and heated to promote the development reaction. This system does not use the above-mentioned processing bath and is advantageous in this respect in terms of environmental protection. It seems that application of the system to a photographic recording system can solve the above-mentioned problems.

In the Pictrography Color System, a pre-prepared dye is contained in a light-sensitive material, and the dye is transferred to an image-receiving material to form colored images thereon. However, this system cannot obtain a resolution required for a photographic material. From the viewpoint of resolution, a system in which an image is formed not on the image-receiving material but on the light-sensitive material is advantageous.

Furthermore, since the dye prepared in advance is contained in the light-sensitive material, a part of the light used for exposure is absorbed by the dye (filtering effect), which is disadvantageous in terms of sensitivity and results in failure to obtain the sensitivity increase required for light-sensitive materials. From the viewpoint of sensitivity, the system in which a coupler capable of forming a dye at the time of development by a coupling reaction with an oxidation product of a developing agent is contained in the light-sensitive material is more advantageous than the system in which a dye has been formed in advance.

However, when rapid image formation by heat development was attempted using a high-sensitivity photographic emulsion and supplying a small amount of water, in a system in which an image is formed on the photosensitive material using a coupling reaction, serious problems arose in that unevenness in the image occurred and a tendency to fog occurred at a practically unacceptable level during storage of the photosensitive material. The unevenness in the image did not occur in the above-mentioned Pictrography Color System. When the photosensitive material having unevenness in the image is used to obtain a color print image for reproducing an original scene, the resulting image is not pleasing. Although it is theoretically possible to read the photosensitive material having the unevenness by such means as a scanner and correct the image information to reproduce the original scene in a hard copy, this method requires an enormous amount of time and is therefore not practical. Accordingly, the unevenness in an image has been a significant obstacle to the rapid processing of a photosensitive photographic material without adversely affecting the environment. Since it is essential to show a way of maintaining the high sensitivity of a photosensitive photographic material and of maintaining the stability during storage of the photosensitive, In addition, fogging has been a serious problem in processing a light-sensitive photographic material in a simple and rapid manner while minimizing adverse effects on the environment.

Documents EP-A-846982 and EP-A-828188 falling under Article 54(3) EPC describe heat-developable materials comprising silver halide grains containing potassium hexachloroiridate or yellow prussiate.

SUMMARY OF THE INVENTION

As is apparent from the foregoing, it is an object of the present invention to solve the problems associated with the above prior art and to achieve the following objects. An object of the present invention is to provide a silver halide color photographic light-sensitive material which is well suited for a simple and rapid process which has little impact on the environment and which has high sensitivity and gives high-quality images without unevenness in the development process. Furthermore, it is also an object of the present invention to provide a method for forming an image which can reduce adverse effects on the environment and give high-quality images without unevenness in a simple and rapid manner using the above-mentioned silver halide color photographic light-sensitive material.

Furthermore, it is another object of the present invention to provide a silver halide color photographic light-sensitive material for photographing which is well suited for a simple and rapid process which causes little environmental impact and which has high sensitivity and excellent storage stability. Furthermore, it is also an object of the present invention to provide a method for forming an image which can reduce adverse effects on the environment and can form an image in a simple and rapid manner using the above-mentioned silver halide color photographic light-sensitive material.

The objects of the present invention as described above are achieved by the following material and the following method:

(1) A light-sensitive silver halide color photographic material comprising a support with a photographic build-up layer applied thereon which contains at least one light-sensitive layer which comprises a light-sensitive silver halide emulsion, a developing agent, a compound capable of forming a dye by a coupling reaction with the oxidation product of a developing agent and a binder, wherein the light-sensitive silver halide color photographic material is, after exposure, combined with a processing material which comprises a support with a build-up layer applied thereon which contains a processing layer which comprises a base and/or a base precursor, in the presence of water which is supplied to the light-sensitive layer of the light-sensitive silver halide color photographic material or to the processing layer of the processing material in an amount in the range of 1/10 to the equivalent of an amount which is required for the maximum swelling of the total applied layers of these materials is required so that the photosensitive layer and the processing layer are opposite each other, and are heated for heat development to form a color image in the silver halide color photographic photosensitive material, in which the silver halide photosensitive emulsion contains at least one ion selected from the group consisting of a metal ion and a metal complex ion each having an electron trap depth of 0.6 eV or less, and contains at least one kind of tabular grains having an aspect ratio in the range of 4 to 100, with the proviso that the at least one ion contained in the silver halide photosensitive emulsion is not a metal ion or metal complex ion derived from potassium hexachloroiridate, and with the proviso that the silver halide photosensitive emulsion is not an emulsion comprising tabular (111) silver chlorobromide grains containing 5 mol% of silver bromide and a metal ion or a metal complex ion derived from yellow Contains prussiate of blood.

(2) A method for forming a color image comprising combining a silver halide color photographic light-sensitive material after exposure thereof and a processing material comprising a support having thereon a build-up layer containing a processing layer containing a base and/or a base precursor, in the presence of water, which is supplied to the light-sensitive layer of the silver halide color photographic light-sensitive material or to the processing layer of the processing material in an amount in the range of 1/10 to the equivalent of an amount required for maximum swelling of the entire coated layers of these materials so that the light-sensitive layer of the silver halide color photographic light-sensitive material and the processing layer are opposed to each other, and heating these materials for heat development to form a color image in the silver halide color photographic light-sensitive material in which the silver halide color photographic light-sensitive material is the above-described silver halide color photographic light-sensitive material.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The silver halide light-sensitive emulsion to be used in the silver halide color photographic light-sensitive material is described below.

The light-sensitive silver halide emulsion contains at least one ion selected from the group consisting of a metal ion and a metal complex ion each having a shallow electron trap depth of 0.6 eV or less, and contains at least one kind of tabular grains having an average aspect ratio in the range of 4 to 100.

Heretofore, it is a technique recognized in the art to incorporate a metal ion and/or a metal complex ion (hereinafter sometimes referred to as "metal ions or metal complex ions") into silver halide emulsion grains. However, this technique uses the above-mentioned metal ions or metal complex ions for processing a color photographic light-sensitive material which requires the use of a processing solution containing a developing agent, or for heat-developing a light-sensitive material for printing to realize high sensitivity, adjust the law of equivalent proportions, control gradation, improve storage stability of a latent image and reduce temperature dependence at the time of exposure. This technique is however, completely different from the technique of the present invention of the silver halide color photographic light-sensitive material.

Accordingly, nowhere is described the effect of the present invention which consists in obtaining high quality images characterized by high sensitivity and non-occurrence of unevenness in a development process by adjusting the depth of electron trap of metal ions or metal complex ions in a light-sensitive silver halide photographic emulsion of high sensitivity designed for heat development. This effect of the present invention was only found after the studies were carried out by the inventors.

In the present invention, the depth of the shallow electron trap is 0.6 eV or less (a maximum of 0.6 eV), more preferably 0.4 eV or less (a maximum of 0.4 eV), and most preferably 0.2 eV or less (a maximum of 0.2 eV).

If metal ions or metal complex ions such as [RhCl₅(H₂O)]2⁻, [RhCl₄(H₂O)₂]⁻, [RuCl₅(NO)]2⁻, [Cr(CN)₆]3⁻, [RhCl₆]3⁻ and RhBr₆]3⁻, each having an electron trap depth greater than 0.6 eV, are used, undesirable effects are that the improvement of the temperature dependence of the developing process is insufficient, that the reduction in sensitivity is significant, and that unevenness of the image tends to occur in a developing process at a high temperature. On the other hand, when metal ions or metal complex ions each having a shallow depth of the electron trap of 0.6 eV or less are used, the above-mentioned undesirable effects are prevented, and the desired effects are that a favorable influence is exerted in the exposure step, that the photosensitive material is less affected by the fluctuation of the conditions of the development process, and that a large latent image can be formed. The reason for this is presumably that the metal ions, etc. each having an electron trap with an appropriate depth prevent the distribution of the latent image, and thereby the latent image becomes larger. In addition, the use of an electron trap with a shallow depth of 0.6 eV or less increases the sensitivity of the photosensitive material and makes it possible to obtain high quality images without unevenness. This desirable effect is significant when the depth is 0.4 eV or less and preferably 0.2 eV or less.

A metal ion and a metal complex ion which can have the above-mentioned shallow depth of the electron trap are given below.

Examples of a metal ion and a metal complex ion which can act as shallow electron traps with a depth of 0.2 eV or less are Pb2+ and [M(CN)xLyNZ], wherein M is selected from the group consisting of Re+, Os2+, Ru2+, Fe2+, Ir3+ and Co3+, x is an integer from 4 to 6, L and N are an inorganic ligand, such as halide ions (e.g., a fluoride ion, a chloride ion, a bromide ion and an iodide ion), SCN⁻, NCS⁻ and H₂O, or an organic ligand such as pyridine, phenanthroline, imidazole and pyrazole, y and z are numbers determined to satisfy the equation x + y + z = 6. When a ligand is present, the coordination number is usually 6.

Examples of a metal ion and a metal complex ion which can act as shallow electron traps with a depth in the range of 0.2 eV to 0.6 eV include ions containing a halide ion ligand or a thiocyanate ion ligand and Ir or Pd. Among these ions, for example, [IrBr₆]⁻³, [Ir(SCH)₆]³⁻ and (IrI₆]³⁻ can be preferably used.

The light-sensitive silver halide emulsion may contain at least one ion selected from the group consisting of a metal ion and a metal complex ion, each of which acts as a relatively deep electron trap, in addition to at least one ion selected from the group consisting of a metal ion and a metal complex ion, each of which acts as a shallow electron trap.

When the light-sensitive silver halide emulsion contains at least one ion selected from the group consisting of a metal ion and a metal complex ion, each having a shallow electron trap depth, together with at least one ion selected from the group consisting of a metal ion and a metal complex ion, each acting as a relatively deep electron trap, the depth is the flat electron trap is preferably 0.2 eV or less (a maximum of 0.2 eV) and more preferably 0.1 eV or less (a maximum of 0.1 eV).

On the other hand, the depth of the relatively deep electron trap is preferably 0.35 eV or more (a minimum of 0.35 eV), and more preferably 0.5 eV or more (a minimum of 0.5 eV).

Examples of a metal ion or a metal complex ion that can act as a relatively deep electron trap include ions containing a halide ion ligand or a thiocyanate ion ligand and Ir, Rh, Ru or Pd, ions containing at least one nitrosyl ligand and Ru, and ions containing a cyano ligand and Cr. Among these ions, for example, [IrBr₆]³⁻, [Ir(SCH)₆]³⁻, [Irl₆]³⁻, [RhCl₅(H₂O)]²⁻, [RhCl₄(H₂O)₆]⁻, [RuCl₅(NO)]²⁻, [Cr(CN)₆]³⁻ [RhCl₆]³⁻, [RhBr₆]³⁻ and [PdCl₆]⁵⁻ are preferably used.

A value for the depth of the electron traps caused by the metal ions and metal complex ions can be obtained by a dynamic measurement and using ESR as described in R. S. Eachus, R. E. Grave and M. T. Olm, Phys. Stat. Sol (b), vol. 88, (1978), page 705.

The depth of the electron trap can vary depending on the central metal ion, the ligand, the symmetry of the point group of the complex (Oh, D4h, C4v) and the halogen composition of the support. The depth of the electron trap can be determined depending on whether the energy level of the lowest unoccupied orbital of the electron of the metal ion or the metal complex ion is lower or higher than that of the lowest conduction band of the silver halide.

If the energy level of the lowest unoccupied orbital of the metal ion is higher than that of the conduction band of the silver halide, a shallow electron trap can be obtained because one electron is loosely bound by the Coulomb force of the central metal ion.

If the energy level of the lowest unoccupied orbital of the metal ion is lower than that of the conduction band of the silver halide, the difference in Energy levels of the conduction band and the lowest unoccupied orbital of the metal ion correspond to the depth of the electron trap, and a relatively deep electron trap can be obtained.

The use of a metal ion or metal complex ion in a light-sensitive silver halide emulsion is known in an emulsion, particularly in a tabular emulsion designed for a light-sensitive photographic material, which requires the use of a processing solution containing a developing agent, as described in, for example, Japanese Patent Laid-Open (JP-A) No. 8-101,474, European Patent No. 0,699,947 and JP-A No. 4-211,144, and the effects of using the metal ion or the metal complex ion include realization of high sensitivity, improvement of the law of equivalent proportions, adjustment of sensitivity and improvement of stability of the emulsion.

However, there is nowhere described the effect that the increase of Dmin during storage of a silver halide color photographic light-sensitive material of the present invention, which is a photographic light-sensitive material containing a developing agent, can be minimized while maintaining high sensitivity when a combination of a metal ion or a metal complex ion each being a shallow electron trap and a metal ion or a metal complex ion each being a relatively deep electron trap is used in the silver halide color photographic light-sensitive material.

Meanwhile, JP-A Nos. 1-116,637, 2-236,542 and 5-181,246, Japanese Patent Application No. 7-122,733 and U.S. Patent No. 5,434,043 describe a method in which Ir is incorporated into the silver halide emulsion of a light-sensitive material containing a developing agent for heat development in order to reduce fogging due to heat development, a method in which iron ions are incorporated into the silver halide emulsion of a light-sensitive material containing a developing agent for heat development in order to impart stability against exposure fluctuation, a method in which polyvalent ions are incorporated into the silver halide emulsion of a light-sensitive material containing a developing agent for heat development in order to reduce fogging due to heat development, a method in which polyvalent ... For example, a method of reducing fogging and increasing sensitivity is disclosed in the prior art, a method in which Ir or Rh is incorporated into the silver halide emulsion having a high silver chloride content of a photosensitive material containing a developing agent for heat development to obtain a high-contrast image even under high illuminance exposure, and a method in which Ir is incorporated into the silver iodobromide of a photosensitive material containing a developing agent, for example, a photosensitive material such as so-called dry silver, to make the photosensitive material suitable for high illuminance. However, these prior art techniques are designed for photosensitive materials for use in printing materials or in printing materials, and are therefore completely different from the technique of the present invention in which the storage stability of the photosensitive material is improved while maintaining the high sensitivity of the silver halide color photographic photosensitive material containing a developing agent and using an emulsion composed of tabular grains. Accordingly, the mere application of these prior art techniques cannot lead to the solution of the objects of the present invention.

The present inventors have found through studies that the increase in Dmin due to the cause inside the developing agent during storage can be minimized, while the high sensitivity is increased if a metal ion and/or a metal complex ion, each of which is a shallow electron trap, are used in combination with a metal ion and/or a metal complex ion, each of which is a relatively deep electron trap.

The phenomenon that a metal ion and/or a metal complex ion, each of which is a relatively deep electron trap, inhibits the increase of Dmin in the developing agent system during storage of a silver halide color photographic light-sensitive material is presumably caused by rendering ineffective the electrons injected from the developing agent into the silver halide during storage and causing an increase of Dmin.

The amount of the above-described metal ion or metal complex ion added to the light-sensitive silver halide emulsion is preferably in the range of 10⁻⁹⁹ to 10⁻² mol per 1 mol of silver halide.

In the light-sensitive silver halide grains, the metal ions and/or metal complex ions (hereinafter referred to as "metal ions or metal complex ions") may be uniformly or locally incorporated into the grains or incorporated on the surface of the grains in an exposed state, or they may be localized in the vicinity of the surface of the grains without being exposed on the surface of the grains.

Epitaxial grains may be crystals of the substrate or crystals of junctions. In a light-sensitive silver halide emulsion having a plurality of phases each containing a different halogen composition, metal ions to be incorporated can be changed according to the halogen compositions.

More concretely, for example, preferred embodiments include forming an epitaxial connection between an AgBr crystal containing Ir ion and a base of tabular AgCl grains containing potassium ferrocyanide, wherein the concentration of the metal ions and/or metal complex ions which are the above-mentioned shallow electron trap and/or relatively deep electron trap to the part at which the dislocation lines in the silver bromide grains having a high edge-type dislocation density are concentrated has a region where a high silver iodide content is localized in the vicinity of the surface thereof, and forming an epitaxial connection crystal containing the above-mentioned metal ions and/or metal complex ions which are a shallow trap to a silver iodobromide base containing the above-mentioned metal ions and/or metal complex ions which are a relatively deep trap. Further, the silver halide grains may have regions, e.g. B. a region where the two kinds of metal ions or metal complex ions exist together, a region where the metal ions or metal complex ions which are a shallow trap exist alone, a region where the metal ions or metal complex ions which are a relatively deep trap exist alone, a region where the two kinds of metal ions or metal complex ions exist together with a region where the metal ions or metal complex ions which are a shallow trap are present alone, and/or a region where the metal ions or metal complex ions which are a relatively deep trap are present alone. Further, the silver halide grains may have a region where absolutely no metal ions or metal complex ions are present together with any of the above five regions.

The addition of the metal ions or metal complex ions described above can be carried out (1) by mixing a solution of the metal salt containing the metal ion or metal complex ion with an aqueous solution of silver salt or an aqueous solution of a halogen compound used in grain formation and continuously adding the resulting mixture to another mixture containing other components to be used in grain formation, or (2) by adding fine photosensitive silver halide grains in which the metal ions or metal complex ions are doped to an emulsion, or (3) by directly adding an aqueous solution of the metal salt containing the metal ions to an emulsion before, during or after grain formation.

When the metal salt is dissolved in a suitable solvent such as water, methanol or acetone, a method of adding an aqueous solution of hydrogen halide (e.g. HCl, HBr), thiocyanic acid or salts thereof, or alkali halide (e.g. KCl, NaCl, KBr, NaBr) to stabilize the solution. It is further preferred to add acid or alkali in stabilizing the solution if necessary.

The amount of these metal ions or metal complex ions in the light-sensitive silver halide emulsion can be measured, for example, by atomic absorption spectroscopy, polarization Zeeman spectroscopy, IPC analysis. The presence of ligands of metal complex ions such as CN-, SCH-, NO⊃min; in the light-sensitive silver halide emulsion can be confirmed by IR absorption (especially FT-IR).

The silver halide composition in the tabular grains of the light-sensitive silver halide emulsion of the present invention is preferably any of silver chloride, silver iodochloride, silver chlorobromide, silver iodochlorobromide and silver iodobromide. In addition, other silver salt such as silver thiocyanate, silver sulfide, silver selenide, silver carbonate and silver phosphate, or an organic silver compound such as a silver/benzotriazole compound, may form a soluble portion in the silver halide grains or may be bound to the silver halide grains.

The above-mentioned halide composition may be the same or different between the grain interior and the grain surface. In the latter case, the silver halide grain is a multilayered grain or a grain having a laminate structure. Furthermore, grains of a silver halide emulsion having a different composition may be bonded to the silver halide grains by an epitaxial bond.

A silver halide emulsion having a high silver chloride content usually has a feature that the development activity is high. It also has a feature that the deterioration of image information at the time when the processed light-sensitive material is read by a scanner without its fixation is insignificant because little fog is formed.

In the present invention, it is possible to use silver halide in which a localized phase in a layered or non-layered state having a different composition is present in the interior of a silver halide grain and/or its surface. The halogen composition of the localized phase can be analyzed by, for example, X-ray diffraction analysis and electron probe X-ray microanalysis. For example, the application of X-ray diffraction to silver halide is described in C. R. Berry and S. J. Marino, "Photographic Science and Technology", vol. 2, p. 149 (1955) and vol. 4, p. 22 (1957). Although the localized phase may be present in the interior, at the edges of the surface, the corners or faces of the grain, it is preferably present in the form of an epitaxial connection to a corner of the grain, as described in JP-A Nos. 58-108,526, 59-133,540, 59-119,350 and 6-194,768 and European Patent Publication No. 0,699,944.

As in the case of conventional photographic light-sensitive materials, silver chloride may be contained even in a silver halide light-sensitive emulsion consisting mainly of silver iodobromide in the present invention. In this case, however, the silver chloride content is preferably 8 mol% or less, and more preferably 3 mol% or less.

In the present invention, it is preferable to use a light-sensitive silver halide emulsion containing silver iodobromide grains having a laminate structure composed of a plurality of layers having different halogen compositions such that the grain has at least one layer having a silver iodide content higher than that of other adjacent layers on the side facing its interior and also higher than that of another adjacent layer facing its outer surface.

In the case where use is made of a light-sensitive silver halide emulsion composed of silver chlorobromide or silver chloride, the emulsion may also contain silver iodide. In this case, however, the silver iodide content is preferably 6 mol% or less, more preferably 2 mol% or less.

Although a silver halide emulsion with a high silver chloride content is not advantageous for the adsorption of a sensitizing dye, the adsorption of the dye can be increased by using grains whose surfaces are enriched in silver iodide or silver bromide.

The halogen composition in the surface of the photosensitive silver halide grains can be measured by X-ray electron spectroscopy for chemical analysis (ESCA).

The distribution of the halogen composition (silver bromide content, silver iodide content, and silver chloride content) among the light-sensitive silver halide grains is preferably narrow. The coefficient of variation of the distribution of the halogen composition is preferably 3 to 30%, more preferably 3 to 25%, and most preferably 3 to 20%. The coefficient of variation means a scatter value (standard deviation) divided by the mean value.

The halogen composition distribution of a single light-sensitive silver halide emulsion can be obtained, for example, using an electron probe X-ray microanalyzer (EPMA).

In a tabular particle of the light-sensitive silver halide emulsion, when the main faces (outer faces having a larger area and consisting of parallel planes) are a (111) plane, the shape of the grain is a parallel multi-twin crystal having two or more parallel twin planes, and when the outer faces are a (100) plane, no twin plane is present. The distance between twin planes may be 0.012 µm or smaller as described in U.S. Patent No. 5,219,720. The distance between (111) main planes divided by the distance between twin planes may also be 15 or more as described in JP-A No. 5-249,585.

When the principal planes are a (111) plane, the grain of the light-sensitive silver halide emulsion is in a triangular or hexagonal shape, or in a more rounded shape suggesting a circle or ellipse when viewed from above.

Even if the main levels are (111) levels, the side levels connecting the main levels may be a (111) level or a (100) level or a mixture of both or may even contain levels of a higher index.

When the outer plane is a (100) plane, the grain of the light-sensitive silver halide emulsion is rectangular in shape when viewed from above.

In the light-sensitive silver halide emulsion used in the present invention, the percentage of the projected area occupied by the tabular grains in the total projected area of all the grains is preferably 80 to 100%, more preferably 90 to 100%, and still more preferably 95 to 100%.

The average grain density of the tabular grains in the light-sensitive silver halide emulsion used in the present invention is preferably 0.005 to 0.2 µm, and more preferably 0.01 to 0.15 µm. The average grain thickness as used herein means the calculated average grain thickness of all the tabular grains in the light-sensitive silver halide emulsion.

The circular equivalent diameter of the average projected area of the tabular grains in the light-sensitive silver halide emulsion is preferably 0.2 to 8 µm, more preferably 0.3 to 5 µm, and most preferably 0.4 to 4 µm.

In the light-sensitive silver halide emulsion, the ratio of the circular equivalent diameter to the average thickness of the tabular grain is called an aspect ratio. The average aspect ratio of the tabular grains of the light-sensitive silver halide emulsion in the present invention is 4 to 100, and preferably 6 to 80. If the aspect ratio is less than 4, the sensitivity is adversely affected. On the other hand, if the aspect ratio exceeds 100, the printing resistance of the grains is undesirably lowered and therefore the grain size distribution tends to become a polydispersion. The average aspect ratio as used herein means a calculated average of the aspect ratios of all the tabular grains contained in the light-sensitive silver halide emulsion.

When the projection plane of the tabular grains of the light-sensitive silver halide emulsion is hexagonal, the proportion of the projected area of the hexagonal tabular grains in which the ratio of the length of the longest side to the length of the shortest side is in the range of 1 to 2 is preferably 50 to 100%, more preferably 70 to 100%, of the total projected area of all the grains contained in the light-sensitive silver halide emulsion. A hexagonal tabular grain in which the ratio is in the vicinity of 1 is preferred.

When the projection plane of the tabular grains of the light-sensitive silver halide emulsion is rectangular, the proportion of the projected area of the rectangular tabular grains in which the ratio of the length of the longest side to the length of the shortest side is in the range of 1 to 2 is preferably 50 to 100%, more preferably 70 to 100%, of the total projected area of all the grains contained in the light-sensitive silver halide emulsion. A square tabular grain in which the ratio is in the vicinity of 1 is preferred.

The shapes of the grains of the light-sensitive silver halide emulsion can be measured under a transmission electron microscope by a carbon replica method in which samples of silver halide grains and latex reference spheres serving as size standards are simultaneously subjected to a shading treatment with, for example, a heavy metal.

In the present invention, it is preferable to use a monodisperse photosensitive silver halide emulsion having a narrow grain size distribution. A monodisperse photosensitive silver halide emulsion as used herein means a photosensitive silver halide emulsion whose grain size distribution has a coefficient of variation of 30% or less. The use of the monodisperse photosensitive silver halide emulsion is described in Trevor Maternaghan, "Surfactant Science Series (Technological Applications of Dispersions)" Vol. 52, p. 373 (1994).

It is also possible to use a polydisperse, light-sensitive silver halide emulsion with a broad grain size distribution.

As described in JP-A Nos. 1-167,743 and 4-223,643, for adjusting the gradation, two or more monodisperse light-sensitive silver halide emulsions each sensitive to the same color but having different grain sizes may be used together. The two or more monodisperse light-sensitive silver halide emulsions may be mixed in the same layer, or these emulsions may form separate layers. It is also possible to use a combination of two or more polydisperse light-sensitive silver halide emulsions or a combination of a monodisperse light-sensitive silver halide emulsion and a polydisperse light-sensitive silver halide emulsion.

Processes for preparing silver bromide emulsions, silver (iodo)bromide emulsions and silver (chloro)bromide emulsions composed of tabular grains having a (111) plane are described, for example, in JP-A Nos. 55-142,329, 58-113,926, 58-113,927 and 58- 113,928, in US Patent Nos. 4,914,014 and 4,942,120, JP-A No. 2-222,940 and in US Patent Nos. 5,013,641 and 4,414,306. Among these Preferred processes are the processes for preparing tabular grains using a polyalkyloxide compound described in U.S. Patent Nos. 5,147,771 to 5,147,773, 5,171,659, 5,210,013 and 5,252,453.

In order to produce tabular grains with a high average aspect ratio in a light-sensitive silver halide emulsion, it is important to grow small twin nuclei. To do this, it is desirable to form the nuclei at low temperature, high pBr, low pH, and with a smaller amount of gelatin or gelatin with a smaller methionine content or gelatin with a smaller molecular weight or a phthalated gelatin derivative and for a shorter period of time.

After the formation of the nuclei, physical ripening is carried out to selectively grow tabular grain nuclei (nucleus having multiple parallel twin planes) solely by eliminating other nuclei, i.e., nuclei of regular structured crystals, nuclei having a single twin plane and nuclei having non-parallel multiple twin planes. Then, a combination of a soluble silver salt and a soluble halogen salt or a silver halide emulsion composed of fine grains having a smaller grain size is added to the obtained nuclei to grow the grains, and an emulsion containing tabular grains is prepared after the growth of the nuclei.

Methods for preparing tabular silver bromide grains or tabular silver (chloro)bromide grains having a (100) plane are described in U.S. Patent No. 4,063,951 (T. G. Bogg) and JP-A No. 58-95,337 (A. Mignot).

Tabular grains of a silver halide emulsion having a high silver chloride content and having a (111) plane are described, for example, in U.S. Patent Nos. 4,399,215, 4,400,463 and 5,217,858 and JP-A No. 2-32. Since the silver halide grain having a high silver chloride content generally has a (100) plane as an outer surface in the absence of an adsorbed substance, a light-sensitive silver halide emulsion containing tabular grains is prepared by a process comprising forming twin nuclei using an adsorptive substance selectively adsorbed on a (111) plane, selectively obtaining nuclei having multiple parallel twin planes by eliminating nuclei of regularly structured crystals, nuclei with a single twin plane, and nuclei with non-parallel, multiple twin planes in a physical maturation stage and growing the selectively preserved nuclei.

An empirical rule for the growth of tabular grains with a (111) plane of a silver halide emulsion with a high silver chloride content is described in "Journal of Photographic Science", Vol. 36, page 182 (1988).

Tabular grains of a silver halide emulsion having a high silver chloride content and having a (100) = plane are described, for example, in U.S. Patent Nos. 4,946,772, 5,275,930 and 5,264,337 and JP-A Nos. 5-281,640 and 5-313,273 and European Patent Publication No. 0,534,395 A1. The key to the preparation of the tabular grains is the growth of the nuclei growing in a tabular shape. For this, it is effective to add bromide ions or iodide ions, or to add a compound that is selectively adsorbed on a specific plane at an early stage of grain formation. After nucleation, a photosensitive silver halide containing tabular grains is produced by physical ripening and growth of the grain. The grains grow by the addition of a combination of a soluble silver salt and a soluble halogen salt or a silver halide emulsion composed of fine grains with a smaller grain size.

The tabular grains are advantageous for sensitivity because the surface area is large and the amount of sensitizing dye adsorbed by the tabular grains is large compared to normal crystals of the same volume.

Accordingly, when compared with the same sensitivity, the volume of tabular grains is smaller than that of normal crystals. When compared with the same sensitivity and the same amount used (by weight), the number of tabular grains used is larger than that of normal crystals used. Therefore, the number of points from which development can start increases, and the graininess, which is an important property in photosensitive material, is excellent.

Furthermore, the amount of silver deposited can be reduced due to the excellent graininess, and radiation fogging, which is an adverse problem for high-sensitivity photosensitive photographic materials, can be significantly inhibited.

Furthermore, reducing the amount of silver deposited is effective in reducing fogging which is responsible for the deterioration of images recorded on a light-sensitive material which has not been subjected to a post-development fixing process at the time of scanning.

In addition, the tabular grains have a high development activity due to their large surface area.

Furthermore, the tabular grains can enable the layer of the photosensitive material to be thin and have excellent sharpness because they are oriented at the time of coating.

From the above description it is clear that tabular grains are of crucial importance for light-sensitive photographic materials.

As long as the pressure resistance of the grains and the monodispersion of the grain size distribution are not impaired, a larger value of the average aspect ratio of the tabular grains is desirable from the viewpoint of sensitivity, granularity, activity and reduction of the amount of silver deposited.

The tabular grains in the light-sensitive silver halide emulsion used in the present invention may have dislocation lines. The dislocation lines as used herein mean linear lattice defects present on the boundary, on the sliding surfaces of crystals, between a region where slip has already occurred and a region where slip has not yet occurred.

With respect to the dislocation lines of photosensitive silver halide crystals, there are references such as (1) C. R. Berry, J. Appl. Phys., 27, 636 (1956), (2) C. R. Berry, D. C. Skilman, J. Appl. Phys., 35, 2165 (1964), (3) J. F. Hamilton, Phot. Sci. Eng., 11, 57 (1967), (4) T. Shiozawa, J. Soc. Phot. Sci. Jap., 34, 16 (1971) and (5) T. Shiozawa, J. Soc. Phot. Sci. Jap., 35, 213 (1972). The dislocation lines of silver halide crystals can be analyzed by X-ray diffraction or direct observation under a low-temperature transmission electron microscope.

When the dislocation lines are directly observed under a transmission electron microscope, a sample of silver halide grain is carefully taken out of a photosensitive silver halide emulsion so that no pressure is applied to cause the dislocation lines in the photosensitive silver halide grains, and is placed on a grid for electron microscopic observation to examine the sample by the transmission method, with the sample being cooled to prevent damage by electron beams (e.g. printout).

In this case, the thicker the silver halide grains become, the less electron beams pass through. Clear observation can be achieved by making use of a high-pressure electron microscope (e.g., greater than or equal to 200 kV for a thickness of 0.25 mm).

Japanese Laid-Open Patent Application (JP-A) No. 63-220,238 describes an invention relating to the introduction of dislocation lines into silver halide grains.

It is shown that tabular grains into which dislocation lines have been introduced are superior to those without dislocation lines in photographic characteristics such as sensitivity and the law of equivalent proportions.

In tabular grains, the position and number of dislocation lines of each grain, observed from the direction perpendicular to the principal plane, can be obtained from photographs of grains taken by means of the aforementioned electron microscope.

When tabular grains in the light-sensitive silver halide emulsion used in the present invention have dislocation lines, the dislocation lines may be optionally introduced into the tip or edge portions of grains or over the entire principal plane, but it is particularly preferred to restrict them to the edge portion.

The term "edge portion" as used herein refers to the outer periphery of the tabular grain and specifically to the portion of the grain on the outside of a line determined as follows. A plurality of lines are drawn from the center of the grain and for each line the content of silver iodide is measured at each of several points along the line. A curve is prepared illustrating the distribution of silver iodide content along the length of the line. The plotted distribution is observed from the point corresponding to the extreme end of the line (i.e., the end opposite the center) and the point at which the distribution first intersects a line indicating the mean silver iodide content in the curve is noted. The location of the line drawn in the grain corresponding to this intersection is noted. This procedure is repeated for each line and the determined locations are connected by a line. The part of the grain on the outside of this line is called the edge part.

In the present invention, when the tabular grain has dislocation lines, the density of these dislocation lines is optional and can be appropriately selected from, for example, more than or equal to 10 lines, 30 lines or 50 lines per grain.

Next, an explanation will be given below of the tabular grain-containing light-sensitive silver halide emulsion and other light-sensitive silver halide emulsions to be used in combination therewith. Hereinafter, both emulsions will be referred to as "silver halide emulsion".

Regarding the general formation of silver halide grains, reference is made to, for example, P. Glafkides, Chimie et Physique Photographique, Paul Montel, 1967, GF Duffin, Photographic Emulsion Chemistry, Focal Press, 1966, VL Zelikman et al., Making and Coating Photographic Emulsion, Focal Press, 1964. Latent images can be formed on the surface of silver halide grains, within the grains or near the grain surface. That is, a method for preparing silver halide emulsions may be selected from an acidic method, a neutral method and an ammonia method. The pH of a liquid phase for forming silver halide may be high to the value at which fogging does not occur. Further, any method selected from a single jet method, a double jet method and a combination thereof may be used as a method for reacting a soluble silver salt with soluble halides.

A method in which grains are formed in the presence of excess silver ion (a reverse method) can also be used. A so-called controlled double jet method in which the pAg value of the liquid phase for the formation of silver halide is kept constant can also be used as a double jet method. According to this method, it is possible to obtain a silver halide emulsion which has a regular crystal system and whose grain size distribution and halogen composition are almost uniform.

As described in U.S. Patent No. 4,879,208, it is also preferable to add an emulsion composed of extremely fine grains which is prepared in situ when the above-mentioned silver halide emulsion is added to the emulsion preparation vessel and then to grow the grains by physical ripening. The emulsion composed of extremely fine grains may be prepared beforehand.

When the silver halide emulsion is prepared, it is preferable to adjust the pAg and pH in the process. The adjustment of the pAg and pH is described in "Photographic Science and Engineering", vol. 6, pp. 159-165 (1962), "Journal of Photographic Science", vol. 12, pp. 242-251 (1964), U.S. Patent No. 3,655,394 and British Patent No. 1,413,748.

As the protective colloid used at the time of preparing the emulsion in the present invention, a gelatin may preferably be used, but other hydrophilic binders may also be used. The hydrophilic binders may be used singly or in combination with gelatin. Examples Examples of hydrophilic binders include derivatives of gelatin, graft polymers of gelatin and other polymers, proteins such as albumin and casein, cellulose derivatives such as hydroxyethyl cellulose and cellulose sulfate, sodium alginate, starch derivatives, polysaccharides, carrageenans, synthetic hydrophilic polymers such as homopolymers and copolymers (polyvinyl alcohol, alkyl-modified polyvinyl alcohol, polyvinyl-N-pyrrolidone, polyacrylic acid, polymethacrylic acid, polyacrylamide, polyvinylimidazole, polyvinylpyrazole) and thioether polymers described in U.S. Patent No. 3,615,624.

As the gelatin at the time of formation of tabular grains, derivatives of gelatin such as lime-treated gelatin, acid-treated gelatin, decalcified gelatin, phthalated gelatin, carbamoyl gelatin, esterified gelatin or low molecular weight gelatin can be preferably used. It is also known that gelatin treated with oxidizing agents such as hydrogen peroxide is effective at the time of formation of tabular grains. An enzyme-treated gelatin described in Bull. Soc. Photo. Japan, No. 16, page 30 (1966) can be used as the low molecular weight gelatin. A hydrolysis product or a degradation product of gelatin obtained by means of an enzyme can also be used.

It is preferable to use a solvent for silver halide at the time of preparing the silver halide emulsion. Examples of a solvent for silver halide include thiocyanates (described in U.S. Patent Nos. 2,222,264, 2,448,534 and 3,320,069), thioether compounds (described in U.S. Patent Nos. 3,271,157, 3,574,628, 3,704,130, 4,297,439 and 4,276,347), thione compounds (described in Japanese Patent Laid-Open (JP-A) Nos. 53-144,319, 53-82,408 and 55-77,737), imidazole compounds (described in Japanese Patent Laid-Open (JP-A) No. 54-100,717), benzimidazole (described in Japanese Patent Publication (JP-B) No. 60-54,662) and amine compounds (described in Japanese Patent Laid-Open (JP-A) No. 54-100,717).

Ammonia may be used in combination with the solvent for silver halide in an amount that does not cause adverse effects. Nitrogen-containing compounds as described in Japanese Patent Publication (JP-B) No. 46-7,781 and Japanese Laid-Open Patent Applications (JP-A) Nos. 60-222,842 and 60- 122,935 may be added at the time of formation of silver halide grains. Examples of solvents for silver halide are described on pages 12 to 18 of Japanese Patent Application Laid-Open (JP-A) No. 62-215,272.

When silver halide emulsion grains are formed, acceleration of grain formation can be achieved by increasing the addition rate, addition amount or addition concentration of the silver salt solution (e.g., an aqueous AgNO3 solution) and the halogen compound solution (e.g., an aqueous KBr solution). Methods for rapidly forming silver halide grains in the above-mentioned manner are described in British Patent No. 1,335,925, U.S. Patent Nos. 3,672,900, 3,650,757 and 4,242,445 and JP-A Nos. 55-142,329, 55-158,124, 58-113,927, 58-113,928, 58-111,934 and 58-111,936.

During the grain preparation process or after the formation of silver halide emulsion grains, the halogen of the silver halide grains can be replaced by a halogen which gives silver halide grains with a low solubility (halogen substitution). This process of halogen substitution is described in "The Fundamentals of Silver Halide Photographic Processes", pages 662-669 and in "The Theory of Photographic Process", 4th ed., pages 97-98. This process can be carried out using a solution of a soluble halide or a fine grain silver halide emulsion.

Thiosulfonates, dichalcogen compounds described in U.S. Patent Nos. 5,219,721 and 5,364,754, lipoic acid, cysteine, elemental sulfur, or an inorganic metal complex such as a cobalt-ammonium complex may be added to an emulsion during and/or after grain formation.

In the step of forming silver halide grains or in physical ripening, metal salts (including complexes) may be present. Examples of metal salts include salts or complexes of cadmium, zinc, thallium, platinum, gallium, copper, nickel, manganese, indium, tin, calcium, strontium, barium, aluminum and bismuth. These compounds may be used singly or in a combination of two or more types thereof. These compounds may be added in the range of about 10-9 to 10⊃min;3 mol per mol of silver halide. These metals may preferably be as water-soluble salts such as an ammonium salt, acetate, nitrate, sulfate, phosphate, hydroxide, a six-coordinate complex, a four-coordinate complex, bromide ion, chlorine ion, cyanide ion, nitrosyl ion, thiocyanide ion, thionitrosyl ion, water, ammonia, oxo and carbonyl, and a combination thereof may preferably be used as a complex ion and a coordination compound. The amount to be added depends on the object, but may generally be in the range of 10-9 to 10-2 mol per mol of silver halide. These metal salts may be uniformly incorporated into silver halide grains, or localized on the surface or inside of grains, or incorporated into a phase where silver bromide grains are localized, or into a carrier for grains containing silver chloride in high concentration. The addition of this compound can be carried out (I) by mixing a solution of the metal salt with an aqueous solution of silver salt or an aqueous solution of a halide compound used in grain formation and continuously adding the resulting mixture to another mixture containing other components to be used in grain formation, or (2) by adding fine silver halide grains in which the metal ions are doped to an emulsion, or (3) by directly adding an aqueous solution of the metal salt to an emulsion before, during or after grain formation.

It may be advantageous to add chalcogenide compounds during the preparation of an emulsion, as described in U.S. Patent No. 3,772,031. In addition to S, Se and Te, cyanate, thiocyanate, selenocyanate, carbonate, phosphate or acetate may be present.

In the process for preparing the light-sensitive silver halide emulsion used in the present invention, it is preferable that a salt removal process is carried out to remove excess salt. For removing salt, usable methods include a noodle washing process with water in which a salt is removed by gelation of gelatin, and a flocculation process using such materials as an inorganic salt containing a polyvalent anion (e.g., sodium sulfate), an anionic surfactant, an anionic polymer (e.g., sodium polystyrenesulfonate) or a gelatin derivative (e.g., aliphatic acylated gelatin, aromatic acylated gelatin and aromatic carbamoylated Gelatin). A method using an ultrafiltration device such as those described in U.S. Patent Nos. 4,758,505 and 4,334,012, Japanese Patent Laid-Open (JP-A) No. 62-113,137 and Japanese Patent Publication (JP-B) No. 59-43,727, a spontaneous flocculation method and a centrifugation method may be used. A flocculation method is usually preferably used.

In the present invention, a photosensitive silver halide emulsion can be used without chemical sensitization, but it is normally chemically sensitized. A sensitization method using a chalcogen such as sulfur sensitization, selenium sensitization or tellurium sensitization, a sensitization method using a noble metal such as gold, platinum or palladium, and a sensitization method by reduction can be used alone or in combination as a chemical sensitization method for the photosensitive silver halide emulsion used in the present invention (see, for example, Japanese Laid-Open Patent Application (JP-A) Nos. 3-110,555 and 5-241,267). Chemical sensitization according to any of the above methods can be carried out in the presence of a nitrogen-containing heterocyclic compound (Japanese Laid-Open Patent Application (JP-A) No. 62-253,159). Besides, an antifoggant, which will be described later, can be added to the silver halide emulsion after its chemical sensitization. More specifically, the methods described in Japanese Laid-Open Patent Application (JP-A) Nos. 5-45,833 and 6240,466 can be used.

The chemical sensitization described above can be carried out at any stage of the production process of the light-sensitive silver halide emulsion. A variety of emulsions can be prepared by changing the production stage at which the chemical sensitization is carried out. The types of sensitization include a type in which chemical sensitization nuclei are embedded in the grain interior, a type in which chemical sensitization nuclei are embedded in a region near the surface of the grain, and a type in which chemical sensitization nuclei are formed on the grain surface. It is also possible to form chemical sensitization nuclei in the grain interior or the surface or in a flat region near the grain surface. For example, although nuclei of a reductive sensitizer are preferably formed in the grain interior, nuclei of a chalcogen sensitizer and/or a gold-chalcogen sensitizer are preferably formed on the grain surface. A variety of combinations are possible according to requirements.

A sulfur sensitizer is composed of an unstable sulfur compound. As a sulfur sensitizer, known sulfur compounds can be used, and the examples include thiosulfates (such as hyposulfite), thiourea (such as diphenylthiourea, triethylthiourea and allylthiourea), allyl isothiocyanate, cystine, p-toluenethiosulfonate, rhodanines and mercapto compounds. The amount of the sulfur sensitizer added is an amount which effectively increases the sensitivity of a photosensitive silver halide emulsion, and a suitable amount varies depending on conditions such as pH, temperatures, relationship with another sensitizer and grain sizes of the photosensitive silver halide emulsion, but a standard amount is 10-9 to 10-1 mol per mol of the photosensitive silver halide.

In the case of selenium sensitization, known unstable selenium compounds are used, and the examples include colloidal metallic selenium, selenourea (such as N,N-dimethylselenourea and N,N-diethylselenourea), selenoketones, selenoamides, aliphatic isoselenocyanates (such as allyl isoselenocyanate), selenocarboxylic acid and esters thereof, selenophosphates, selenides such as diethylselenide and diethyldiselenide, and phosphineselenide. Although the amount added varies depending on the conditions as in the case of the sulfur sensitizer, a standard amount is preferably 10-10 to 10-1 mol per mol of the photosensitive silver halide.

In addition to the above-mentioned chalcogen sensitization, sensitization by a noble metal is also possible in the present invention. In the case of gold sensitization, the valence of gold may be +1 or +3, and a variety of gold compounds may be used. Typical examples of the gold compounds as the sensitizer include chloroauric acid, potassium chloroaurate, auritrichloride, potassium aurithiocyanate, potassium iodoaurate, tetraauric acid, ammonium aurothiocyanate, pyridyltrichlorogold, gold sulfide, gold selenide and gold telluride.

Although the amount of the gold sensitizer added varies depending on the conditions, a standard amount is preferably 10-10 to 10-1 mol per mol of the silver halide.

The addition of the gold sensitizer can be done simultaneously with the sensitization by sulphur, selenium or tellurium. It can be done during or before the sensitization by sulphur, selenium or tellurium, or it can be done after the sensitization by sulphur, selenium or tellurium. Alternatively, it is also possible to do the gold sensitization alone.

In the present invention, when sensitization of an emulsion is carried out by sulfur, selenium, tellurium or by gold, the pAg and the pH of the emulsion are not particularly limited. However, preferably, the pAg is in the range of 5 to 11 and the pH is in the range of 3 to 10, and more preferably, the pAg is in the range of 6.8 to 9.0 and the pH is in the range of 5.5 to 8.5.

When a metal ion in the form of a cyan complex is used at the time of grain formation and gold sensitization is carried out, in order to achieve a high sensitization value, it is preferable to add a metal ion such as a zinc ion which forms a coordination bond with gelatin at a stage before chemical sensitization or at the time when gelatin is dispersed.

In the present invention, a noble metal other than gold may also be added as a chemical sensitizer. Examples of noble metal other than gold as a sensitizer include salts and complexes of platinum, palladium, iridium and rhodium.

Palladium compounds in the form of salts with a valence of 2 or 4 can be used. For example, K2PdCl4 and Na₂PdCl₆ are preferred.

A gold compound and a noble metal compound can be used in combination with a thiocyanate or selenocyanate.

In the present invention, it is further possible to carry out reductive sensitization of the silver halide emulsion. The reductive sensitization is preferably carried out during grain formation, before or during chemical sensitization, but after grain formation or after chemical sensitization.

The reductive sensitization as used herein means any of the following methods: a method in which a reductive sensitizer is added to a light-sensitive silver halide emulsion; a silver ripening method in which grains of the emulsion are grown or ripened in a low pAg environment of pAg 1 to 7; and a high pH ripening method in which grains of the emulsion are grown or ripened in a high pH environment of pH 8 to 11. Two or more of these methods may be used together.

The reductive sensitizers to be used in the present invention are known compounds, examples of which include sulfites, ascorbic acid, stannous salts, amines and polyamines, hydrazine derivatives, formamidine sulfinic acid, silane compounds and borane compounds. In the present invention, these known compounds may be used alone or in combination of two or more of them. Preferred reductive sensitizers are stannous chloride, thiourea dioxide, dimethylamine borane, L-ascorbic acid and aminoiminomethanesulfinic acid. The alkynylamine compounds described in US Pat. No. 5,389,510 are also effective compounds. Although the amount of the reductive sensitizer added varies depending on the conditions of the emulsion, a suitable amount is in the range of 10⁻⁹ to 10⁻⁹ to 10⊃min;² mol per mole of silver halide.

In addition to the addition of reductive sensitizers, reductive sensitization can also be carried out by introducing hydrogen gas or by using hydrogen evolved from electrolysis.

Reductive sensitization can be performed alone, but it can also be performed in combination with the chalcogen or gold sensitization mentioned above.

The reductive sensitizer is dissolved in a solvent such as water, alcohol, glycol, ketone, ester or amide, and the solution is added to the photosensitive silver halide emulsion during grain formation and/or after grain formation. When the reductive sensitizer is added during grain formation, it is preferred that it be added to the emulsion at an appropriate stage of grain formation, although it may be introduced into a reaction vessel beforehand. It is also possible to add the reductive sensitizer to either an aqueous solution of a halide or an aqueous solution of a silver salt so as to precipitate the grains of a photosensitive silver halide emulsion when these solutions are mixed. Furthermore, the reductive sensitizer solution may be divided into portions so that these portions are added several times, or the reductive sensitizer solution may be added continuously over a long period of time.

The amount of the light-sensitive silver halide emulsion applied is in the range of 1 mg to 10 g/m², based on the weight of silver.

It is preferable to use an oxidizing agent for silver during the production process of the photosensitive silver halide emulsion to be used in the present invention. An oxidizing agent for silver as used herein means a compound which causes the conversion of metallic silver into silver ion. Especially effective is a compound which converts very fine silver grains formed as a by-product, particularly in the grain formation step or the chemical sensitization step of the photosensitive silver halide emulsion, into silver ion. The silver ion thus formed may form a silver salt having a low solubility in water, such as silver halide, silver sulfide or silver selenide, or it may form a silver salt having a high solubility in water, such as silver nitrate. The oxidizing agent for silver may be an inorganic substance or an organic substance.

Examples of the inorganic oxidizing agent include ozone, hydrogen peroxide and adducts thereof (such as NaBO₂·H₂O₂·3H₂O, 2NaCO₃·3H₂O₂, Na₄P₂O₇·2H₂O₂ and 2Na₂SO₄·H₂O2·2H₂O), oxygen acid salts, e.g. B. peroxyacid salts (such as K2S2 O8 , K2 C2 O6 , K2 P2 O8 ), peroxy complex compounds (such as K2 [Ti(O2 )C2 O4 ]·3H2 O, 4K2 SO4 · Ti(O2 )OH·SO4 ·2H2O, Na3[VO(O2)(C2H4)2] ·6H2O, Permanganates (such as KMnO₄) and chromates (such as K₂Cr₂O₇), halogen elements such as iodine and bromine, perhalic acid salts (such as potassium periodate), salts of metals with a higher valence (such as potassium hexacyanoferrate(III)) and thiosulfonates.

Examples of the organic oxidizing agent include quinones such as p-quinone, organic peroxides such as peracetic acid and perbenzoic acid, and compounds capable of releasing active halogen (such as N-bromosuccinimide, chloramine T and chloramine B).

In the present invention, preferred examples of the oxidizing agent for the above-mentioned silver are ozone, hydrogen peroxide and adducts thereof, inorganic oxidizing agents such as halogen elements and thiosulfonates, and organic oxidizing agents such as quinones. The disulfide compounds described in European Patent Publication No. 0,627,657 A2 are also preferred compounds.

It is preferable to use the above-mentioned reductive sensitizer in combination with the oxidizing agent for silver. For example, the reductive sensitization may be carried out after the use of the oxidizing agent, or the order may be reversed, or else the oxidizing agent and the reductive sensitizer may be present at the same time. Either of these methods may be used in the grain formation step or in the chemical sensitization step.

In order to prevent fogging or to stabilize the photographic characteristics during the manufacturing process, storage or photographic processing of the light-sensitive silver halide photographic emulsion used in the present invention, a variety of compounds can be added to the emulsion. These compounds are known as antifoggants or as stabilizers, and examples of these compounds include thiazoles such as benzothiazolium salts, nitroimidazoles, nitrobenzimidazoles, chlorobenzimidazoles, bromobenzimidazoles, mercaptothiazoles, mercaptobenzothiazoles, mercaptobenzimidazoles, mercaptothiadiazoles, aminotriazoles, benzotriazoles, nitrobenzotriazoles and mercaptotetraazoles (particularly 1-phenyl-5-mercaptotetrazole), mercaptopyrimidines, mercaptotriazines, thioketone compounds, such as oxazoline, and azaindenes such as triazaindenes, tetraazaindenes (particularly 4-hydroxy-substituted (1,3,3a,7)-tetraazaindenes) and pentaazaindenes. These are described, for example, in U.S. Patent Nos. 3,954,474 and 3,982,947 and in Japanese Patent Publication (JP-B) No. 52-28,660. One of the preferred compounds is the compound described in JP-A No. 63-212,932.

Depending on the purposes, the antifoggant and the stabilizer may be added at an appropriate stage, e.g., before grain formation, during grain formation, after grain formation, in the rinsing stage, in the dispersing stage after rinsing, before chemical sensitization, during chemical sensitization, after chemical sensitization, or before coating. In addition to the main purpose of preventing fogging and achieving stabilization, the antifoggant and the stabilizer may be added to the emulsion for other purposes, such as controlling grain habit, reducing grain size, reducing solubility of grains, controlling chemical sensitization, and controlling the arrangement of dyes.

In order to exhibit the effect of the present invention, it is preferable that the light-sensitive silver halide photographic emulsion to be used in the present invention undergoes spectral sensitization by a methionine dye. Examples of usable dyes include cyanine dyes, merocyanine dyes, complex cyanine dyes, complex merocyanine dyes, holopolar cyanine dyes, hemicyanine dyes, styryl dyes and hemioxonol dyes. Particularly usable dyes are cyanine dyes, merocyanine dyes and complex merocyanine dyes. Any of the nuclei usually used as a basic heterocyclic ring in a cyanine dye is applicable to the above-mentioned dyes. Thus, examples of applicable nuclei include a pyrroline nucleus, an oxazoline nucleus, a thiozoline nucleus, a pyrrole nucleus, an oxazole nucleus, a thiazole nucleus, a selenazole nucleus, an imidazole nucleus, a tetrazole nucleus, a pyridine nucleus, a nucleus having an alicyclic hydrocarbon ring condensed to any of the above nuclei, and a nucleus having an aromatic hydrocarbon ring condensed to any of the above nuclei, such as an indolenine nucleus, a benzindolenine nucleus, an indole nucleus, a benzoxazole nucleus, a naphthooxazole nucleus, a benzothiazole nucleus, a naphthothiazole nucleus, a benzoselenazole nucleus, a benzimidazole nucleus. and a quinoline nucleus. These nuclei can be bonded to a carbon atom as a substituent.

A 5- or 6-membered heterocyclic nucleus such as a pyrazolin-5-one nucleus, a thiohydantoin nucleus, a 2-thiooxazolidine-2,4-dione nucleus, a thiazolidine-2,4-dione nucleus, a rhodanine nucleus and a thiobarbituric acid nucleus is applicable as a nucleus having a ketomethylene structure for a merocyanine dye or a complex merocyanine dye.

Although these sensitizing dyes can be used alone, they can also be used in a combination thereof. A combination of these sensitizing dyes is often used, especially for the purpose of supersensitization. Typical examples of these dyes are disclosed, for example, in US Patent Nos. 2,688,545, 2,977,229, 3,397,060, 3,522,052, 3,527,641, 3,617,293, 3,628,964, 3,666,480, 3,672,898, 3,679,428, 3,703,377, 3,769,301, 3,814,609, 3,837,862 and 4,026,707, in British Patent Nos. 1,344,281 and 1,507,803, in JP-B Nos. 424936 and 53-12,375 and in JP-A Nos. 52-110,618 and 52-109,925.

The light-sensitive silver halide emulsion to be used in the present invention may contain a compound which is a dye having no spectral sensitizing effect of its own or a compound which can not substantially absorb visible light but which has a supersensitizing effect.

The above-mentioned sensitizing dye may be added to the emulsion at any stage which has been known to be effective in the emulsion manufacturing process. As a most commonly used practice, the sensitizing dye is added to the emulsion at a stage after completion of chemical sensitization but before coating. However, the above-mentioned sensitizing dye may be added to the emulsion at the stage of chemical sensitization so that spectral sensitization is carried out simultaneously with chemical sensitization, as described in U.S. Patent Nos. 3,628,969 and 4,225,666. Alternatively, as described in JP-A No. 58-113,928, the above-mentioned sensitizing dye may be added to the emulsion before chemical sensitization, or it may be added before complete formation of the precipitate. of the silver halide particles so that spectral sensitization starts at this stage. Further, as described in U.S. Patent No. 4,225,666, the above-mentioned sensitizing dye may be divided into portions to be added separately so that a part is added to the emulsion before chemical sensitization and the rest is added to the emulsion after chemical sensitization. Further, as described in U.S. Patent No. 4,183,756 and other publications, the above-mentioned sensitizing dye may be added to the emulsion at any stage during the formation of the photosensitive silver halide grains.

Although the amount added is generally in the range of 4 x 10-6 to 8 x 10-3 mol per mol of silver halide, a more effective amount is in the range of 5 x 10-5 to 2 x 10-3 mol per mol of silver halide in the case where the grain size of the silver halide emulsion is in the range of 0.2 to 1.2 µm, which is a preferable range of the grain size.

The light-sensitive silver halide emulsion may contain a variety of additives as described above, and other additives may also be used depending on the purposes.

Further details of these additives are described in Research Disclosure (RD) Nos. 17,643 (December 1978), 18,716 (November 1979) and 308,119 (December 1989). The relationship in the specification is shown below.

(RC: right column, LC: left column

European Patent Publication No. 0,565,096 A1 (published on October 13, 1993) and the patent publications cited therein describe various techniques that can be used in the light-sensitive silver halide emulsion and also in the silver halide color photographic material using the light-sensitive silver halide emulsion, including techniques such as the arrangement of layers, light-sensitive silver halide emulsions, dye-forming couplers, functional couplers such as a DIR coupler, additives and developing processes. The relevant locations in the description are shown below.

1. Layer structure:

Lines 23-35 on page 61, line 41 on page 61 - line 14 on page 62

2. Intermediate layer: lines 36-40 on page 61

3. Multilayer functional layer: lines 15-18 on page 62

4. Halogen composition of silver halide: lines 21-25 on page 62

5. Grain habit of silver halide: lines 26-30 on page 62

6. Grain size of silver halide: lines 31-34 on page 62

7. Process for preparing an emulsion: lines 35-40 on page 62

8. Grain size distribution of silver halide: lines 41-42 on page 62

9. Tabular grain: lines 43-46 on page 62

10. Internal structure of the grain: lines 47-53 on page 62

11. Latent image forming type emulsion:

Line 54 on page 62 - Line 5 on page 63

12. Physical ripening/chemical ripening of the emulsion:

Lines 6-9 on page 63

13. Use of a mixture of emulsions: lines 10-13 on page 63

14. Fogged emulsion: lines 14-31 on page 63

15. Non-light-sensitive emulsion: lines 32-43 on page 63

16. Amount of silver plating: lines 49-50 on page 63

17. Photographic supplement: Research Disclosure (RD)

18. Formaldehyde scavengers: lines 54-57 on page 64

19. Mercapto-based antifoggants: lines 1-2 on page 65

20. Fogging agent releasing compound: lines 3-7 on page 65

21. Dye: lines 7-10 on page 65

22. Color couplers in general: lines 11-13 on page 65

23. Yellow, magenta and cyan couplers: lines 14-25 on page 65

24. Polymer couplers: lines 26-28 on page 65

25. Diffusible dye forming couplers: lines 29-31 on page 65

26. Colored Coupler: Lines 32-38 on page 65

27. Functional coupler in general: lines 39-44 on page 65

28. Bleach promoter releasing coupler: lines 45-48 on page 65

29. Development promoter releasing copper: lines 49-53 on page 65

30. Other DIR coupler: Line 54 on page 65 - Line 4 on page 66

31. Method for dispersing coupler: lines 5-28 on page 66

32. Antiseptic/anti-mould agent: lines 29-33 on page 66

33. Types of photosensitive materials: lines 34-36 on page 66

34. Thickness of the photosensitive layer and swelling rate:

Line 40 on page 66 - Line 1 on page 67

35. Back layer: lines 3-8 on page 67

36. Development processes in general: lines 9-11 on page 67

37. Development solution and development resources: lines 12-30 on page 67

38. Addition to a development solution: lines 31-44 on page 67

39. Reversal procedure: lines 45-56 on page 67

40. Percentage of openness to a development solution:

Line 57 on page 67 - Line 12 on page 68

41. Development time: lines 13-15 on page 68

42. Bleach-fixing/bleaching/fixing: line 16 on page 68 - line 31 on page 69

43. Automatic developer: lines 32-40 on page 69

44. Washing with water/rinsing/stabilization:

Line 41 on page 69 - Line 18 on page 70

45. Addition of a processing solution/reuse:

Lines 19-23 on page 70

46. Incorporation of a developing agent into a light-sensitive material:

Lines 24-33 on page 70

47. Temperature of the development process: lines 34-38 on page 70

48. Use in a film with a lens: lines 39-41 on page 70

The coating weight of the light-sensitive silver halide emulsion to be used in the present invention is preferably in the range of 1 mg to 10 g/m², and more preferably in the range of 500 mg to 5 g/m², in terms of the weight of silver.

Since the silver halide color photographic light-sensitive material of the present invention contains a color-forming developing agent whose color can be obtained by developing Silver can form color by reacting with a coupler described later, the light-sensitive material of the present invention does not require the use of a processing solution containing a color-forming developing agent, thereby reducing adverse effects on the environment and enabling the light-sensitive material of the present invention to be processed easily and quickly.

In order to allow the developing agent contained in the light-sensitive material of the present invention to exert its effect, color formation and development are carried out by a method which comprises bringing the silver halide color photographic light-sensitive material after exposure thereof and a processing material containing a support with a processing layer containing a base precursor and/or a base to be described later in the presence of water supplied to the light-sensitive layer of the silver halide color photographic light-sensitive material and/or the processing layer of the processing material in an amount ranging from 1/10 to the equivalent of an amount required for maximum swelling of the entire coated layers of these materials so that the light-sensitive layer and the processing layer face each other, and heating these materials for heat development to form a color image in the silver halide color photographic light-sensitive material.

The light-sensitive material of the present invention reduces the adverse effects on the environment accompanying development using a developing solution. However, the light-sensitive material of the present invention can also be developed by an activator method using an alkaline processing solution or by a development method using a processing solution containing a developing agent and a base.

The developing agent may be added in the form of a liquid dispersion obtained by a process which comprises mixing the developing agent with a high boiling point solvent (e.g. alkyl esters of phosphoric acid and alkyl esters of phthalic acid), dissolving the mixture in a low boiling point solvent (e.g. ethyl acetate and methyl ethyl ketone) and Dispersing the solution in water by an emulsifying dispersion method known in the art. The developing agent may be added in the form of a solid dispersion obtained by a method described in JP-A No. 63-271,339. It is also preferable to emulsify the developing agent together with a coupler (a compound which produces a color by reacting with the oxidation product of the developing agent) described later.

In the present invention, the amount of the developing agent added is preferably 0.01 to 20 mol, more preferably 0.1 to 10 mol, per mol of silver. Besides, the amount of the developing agent added is preferably 0.01 to 100 mol, more preferably 0.1 to 10 mol, per mol of coupler.

In the present invention, it is preferable to use a compound represented by any one of formulas (I), (II), (III) or (IV) as a developing agent. General Formula (I) General formula (II) General formula (III) General formula (IV)

Details of these development resources are described below.

The compounds represented by formula (I) are generally referred to as sulfonamide phenols and are compounds known in the art. In these compounds, preferably at least one of the substituents R1 to R5 has a ballast group having 8 or more carbon atoms to impart oil solubility to the compound.

In formulas (I) to (IV), R₁ to R₄ are each a hydrogen atom, a halogen atom (such as a chlorine atom and a bromine atom), an alkyl group (such as methyl, ethyl, isopropyl, n-butyl and t-butyl groups), an aryl group (such as phenyl, tolyl and xylyl groups), an alkylcarbonamide group (such as acetylamino, propionylamino and butyloylamino groups), an arylcarbonamide group (such as benzoylamino), an alkylsulfonamide group (such as methanesulfonylamino and ethanesulfonylamino groups), an arylsulfonamide group (such as benzenesulfonylamino and toluenesulfonylamino groups), an alkoxy group (such as methoxy, ethoxy and butoxy groups), an aryloxy group (such as a phenoxy group), an alkylthio group (such as methylthio, ethylthio and butylthio groups), an arylthio group (such as phenylthio and tolylthio groups), an alkylcarbamoyl group (such as methylcarbamoyl, Dimethylcarbamoyl, ethylcarbamoyl, diethylcarbamoyl, dibutylcarbamoyl, piperidylcarbamoyl and morpholylcarbamoyl), an arylcarbamoyl group (such as phenylcarbamoyl, methylphenylcarbamoyl, ethylphenylcarbamoyl and benzylphenylcarbamoyl groups), a carbamoyl group, an alkylsulfamoyl group (such as methylsulfamoyl. Dimethylsulfamoyl, ethylsulfamoyl, diethylsulfamoyl, dibutylsulfamoyl, piperidylsulfamoyl and morpholylsulfamoyl), an arylsulfamoyl group (such as phenylsulfamoyl, methylphenylsulfamoyl, ethylphenylsulfamoyl and benzylphenylsulfamoyl groups), a sulfamoyl group, a cyano group, an alkylsulfonyl group (such as methanesulfonoyl and ethanesulfonyl groups), an arylsulfonyl group (such as phenylsulfonyl, 4-chlorophenylsulfonyl and p-toluenesulfonyl groups), an alkoxycarbonyl group (such as methoxycarbonyl, ethoxycarbonyl and butoxycarbonyl groups), an aryloxycarbonyl group (such as a phenoxycarbonyl group), an alkylcarbonyl group (such as acetyl, propionyl and butyloyl groups), an arylcarbonyl group (such as benzoyl and alkylbenzoyl groups) or an acyloxy group (such as acetyloxy, propionyloxy and butyloyloxy groups). Among the groups R₁ to R₄, R₂ and R₄ are each preferably a hydrogen atom. Further, the sum of the Hammett constants σp of R₁ to R₄ is preferably 0 or greater. In the formula (I) to (IV), R₅ represents an alkyl group (such as methyl, ethyl, butyl, octyl, lauryl, cetyl and stearyl groups), an aryl group (such as phenyl, tolyl, xylyl, 4-methoxyphenyl, dodecylphenyl, chlorophenyl, trichlorophenyl, nitrochlorophenyl, triisopropylphenyl, 4-dodecyloxyphenyl and 3,5-di-(methoxycarbonyl) groups) or a heterocyclic group (such as a pyridyl group).

The compounds represented by formula (II) are generally referred to as carbamoylhydrazines and are compounds known in the art. In these compounds, R5 or a substituent attached to a ring has a ballast group having 8 or more carbon atoms.

In the formula (II), Z represents a group of atoms forming an aromatic ring. The aromatic group represented by Z should be sufficiently electron-attractive to impart silver-developing activity to the compound. From this point of view, a nitrogen-containing aromatic ring or an aromatic ring such as a benzene ring having an electron-attracting substituent is preferably used. In this sense, preferred aromatic rings include a pyridine ring, a pyradine ring, a pyrimidine ring, a quinoline ring and a quinoxaline ring. In the case of a benzene ring, examples of the substituents include a halogen atom (such as a chlorine atom and a bromine atom), an alkylcarbamoyl group (methylcarbamoyl, dimethylcarbamoyl, ethylcarbamoyl, diethylcarbamoyl, dibutylcarbamoyl, piperidylcarbamoyl and morpholinocarbamoyl), an arylcarbamoyl group (such as phenylcarbamoyl, methylphenylcarbamoyl, ethylphenylcarbamoyl and benzylphenylcarbamoyl groups), a carbamoyl group, an alkylsulfamoyl group (such as methylsulfamoyl, dimethylsulfamoyl, ethylsulfamoyl, diethylsulfamoyl, dibutylsulfamoyl, piperidylsulfamoyl and morpholylsulfamoyl), an arylsulfamoyl group (such as phenylsulfamoyl, methylphenylsulfamoyl, ethylphenylsulfamoyl and benzylphenylsulfamoyl groups), a Sulfamoyl group, a cyano group, an alkylsulfonyl group (such as methanesulfonyl and ethanesulfonyl groups), an arylsulfonyl group (such as phenylsulfonyl, 4-chlorophenylsulfonyl and p-toluenesulfonyl groups), an alkoxycarbonyl group (such as methoxycarbonyl, ethoxycarbonyl and butoxycarbonyl groups), an aryloxycarbonyl group (such as a phenoxycarbonyl group), an alkylcarbonyl group (such as acetyl, propionyl and butyloyl groups) and an arylcarbonyl group (such as benzoyl and alkylbenzoyl groups). The sum of the Hammett constants σ of the above substituents is 1 or greater.

The compounds represented by formula (III) are generally referred to as carbamoylhydrazones. The compounds represented by formula (IV) are generally referred to as sulfonylhydrazines. Both groups of these compounds are known in the art. In these compounds, at least one of the substituents R₅ to R₈ has a ballast group having 8 or more carbon atoms.

In the formula (III), R₆ represents an alkyl group (such as methyl and ethyl groups). X represents an oxygen atom, a sulfur atom, a selenium atom or an alkyl- or aryl-substituted tertiary nitrogen atom. Preferably, X represents an alkyl-substituted tertiary nitrogen atom. R₇ and R₈ each represents a hydrogen atom or a substituent (examples of which include the above examples of substituents on the benzene ring for Z). R₇ and R₈ may be bonded to each other to form a double bond or a ring.

Among the compounds represented by formulae (I) to (IV), the compounds represented by the formulae (I) and (II) are preferred from the viewpoint of superior storage stability of the photosensitive raw material.

In the above compounds, the substituents R₁ to R₈ may each have a substituent, examples of which include the above examples of substituents on the benzene ring for Z.

Concrete examples of the compounds represented by formulas (I) to (IV) are given below, but a developing agent used in the present invention is not limited to these examples.

The above compounds can be synthesized by conventional methods. Reaction routes for the syntheses are briefly described below. Synthesis of developing agent D-2 Synthesis of developing agent D-27 Synthesis of developing agent D-22

In the present invention, a combination of a developing agent and a coupler can be used, and examples of such a combination include a combination of a p-phenylenediamine as a developing agent and a phenol or active methylene coupler described in U.S. Patent No. 3,631,256, and a combination of a p-aminophenol as a developing agent and an active methylene coupler described in U.S. Patent No. 3,761,270.

Further, the use of a combination of a sulfonamide phenol and a 4-equivalent coupler in a light-sensitive material described in U.S. Patent No. 4,021,240 and JP-A No. 60-128,438 is preferred because this combination ensures excellent storage stability of the light-sensitive raw material.

When a developing agent is included in the present invention, a developing agent precursor may be used, examples of which include an indoaniline-based compound described in U.S. Patent No. 3,342,597, a Schiff base type compound described in U.S. Patent No. 3,342,599 and Research Disclosure Nos. 14,850 and 15,159, an aldol compound described in Research Disclosure No. 13,924, a metal salt complex described in U.S. Patent No. 3,719,492, and a urethane-based compound described in JP-A No. 53-135,628.

Other combinations, i.e., a combination of a sulfonamide phenol as a developing agent and a coupler as described in Japanese Patent Application No. 7-180,568 and a combination of a hydrazine as a developing agent and a coupler as described in Japanese Patent Application Nos. 749,287 and 7-63,572 are also preferred for use in the light-sensitive material of the present invention.

In the case where a non-diffusible developing agent is used, an electron transport agent and/or a precursor thereof may be used, if necessary, in the light-sensitive material of the present invention to accelerate the electron transport between the non-diffusible developing agent and the silver halide to be developed. The use of electron transport agents and precursors thereof described in US Patent No. 5,139,919 and European The use of methods for introducing the electron transport agent and/or precursor thereof stably into a layer described in Japanese Patent Laid-Open (JP-A) Nos. 2-230,143 and 2,235,044 is particularly preferred in the present invention.

An electron transport agent or a precursor thereof can be selected from the above-mentioned developing agents or precursors thereof. The mobility of the electron transport agent or a precursor thereof is preferably greater than that of a non-diffusible developing agent (electron donor). Particularly preferred electron transport agents are 1-phenyl-3-pyrazolidones or aminophenols.

A precursor of an electron donor described in Japanese Patent Application Laid-Open (JP-A) No. 3-160,443 is also preferred for use in the light-sensitive material of the present invention.

For such purposes as preventing color mixing, improving color reproduction and the like, a reducing agent may be used in an intermediate layer or in a protective layer. The reducing agents described in European Patent Application Laid-Open Nos. 524,649 and 357,040 and Japanese Patent Application Laid-Open (JP-A) Nos. 4-249,245, 2-46,450 and 63-186,240 are preferred for use in the present invention. Also usable are development inhibitor-releasing reducing agents described in Japanese Patent Publication (JP-B) No. 3-63,733, Japanese Laid-Open Applications (JP-A) Nos. 1-150,135, 246,450, 2-64,634 and 343,735 and European Laid-Open Application No. 451,833.

Further, a precursor of a developing agent which does not have reducing properties by itself but has reducing properties under the action of a nucleophilic reagent or heat in the developing process can be used in the light-sensitive material of the present invention.

The silver halide color photographic light-sensitive material of the present invention may contain any of the following reducing agents, examples of which are the reducing agents and precursors thereof described in U.S. Patent Nos. 4,500,626, columns 49-50, 4,839,272, 4,330,617, 4,590,152, 5,017,454 and 5,139,919, Japanese Patent Laid-Open (JP-A) Nos. 60-140,335, pages 17-18, 57-40,245, 56-138,736, 59-178,458, 59-53,831, 59-182,449, 59-182,450, 60-119,555, 60-128,436, 60-128,439, 60-198,540, 60-181,742, 61-259,253, 62-244,044, 62-131,253, 62-131,256, 64-13,546, pages 40-57 and 1-120,553 and in the European laid open application No. 220,746 A2, pages 78-96.

Furthermore, a combination of reducing agents described in U.S. Patent No. 3,039,869 can also be used in the present invention.

The light-sensitive material of the present invention contains a compound (coupler) which forms a dye by a coupling reaction with the oxidation product of the developing agent.

The coupler to be used in the present invention may be a 4-equivalent coupler or a 2-equivalent coupler. In these couplers, the non-diffusible group may form a polymer chain. Details of the couplers are described, for example, in: B. in T. H. James, The Theory of the Photographic Process, 4th edition, pages 291-334, pages 354 -361 and in Japanese Patent Application Laid-Open (JP-A) Nos. 58-123,533, 58-149,046, 58-149,047, 59-111,148, 59-124,399, 59-174,835, 59-231,539, 59-231,540, 60-2,950, 60-2,951, 60-14,242, 60-23,474, 60-66,249, 8-110,608, 8-146,552 and 8-146,578.

Further, the following couplers are preferably used in the present invention.

Yellow couplers: couplers represented by formulas (I) and (II) in EP 502,242 A; couplers represented by formulas (1) and (2) in EP 513,496 A; couplers represented by general formula (I) described in claim 1 of Japanese Patent Application Laid-Open (JP-A) No. 5-307,248; couplers represented by general formula (D) in US Patent No. 5,066,576, column 1, lines 45 to 55 Couplers; couplers represented by the general formula (D) in Japanese Patent Application Laid-Open (JP-A) No. 4-274,425, paragraph 008; couplers described in EP 498,381 A1, claim 1 on page 40; couplers represented by the formula (Y) in EP 447,969 A1, page 4; and couplers represented by the general formulas (I) to (IV) in US Patent No. 4,476,219, column 7, lines 36 to 58.

Magenta couplers: couplers described in Japanese Patent Application Laid-Open (JP-A) Nos. 3-39,737, 6-43,611, 5-204,106 and 4-3,626.

Cyan couplers: couplers described in Japanese Laid-Open Patent Application (JP-A) Nos. 4-204,843 and 4-43,345 and Japanese Patent Application No. 4-23,633.

Polymeric couplers: couplers described in Japanese Patent Application Laid-Open (JP-A) No. 2-44,345.

The couplers described in US 4,366,237, GB 2,125,570, EP 96,570 and DE 3,234,533 are preferred as a coupler that produces a dye with a suitable diffusing property.

In order to correct the unnecessary absorption of a coloring dye, the silver halide color photographic light-sensitive material in the present invention may contain a functional coupler, for example, the yellow colored cyan coupler and the yellow colored magenta coupler described in EP 456,257 A1, the magenta colored cyan coupler described in US 4,833,069, and the colorless masking coupler represented by the formula (2) in US 4,837,136 and by the formula (A) in claim 1 of WO 92111,575 (particularly the compounds shown on pages 36-45).

In the present invention, it is preferred to use a coupler or other compound that reacts with the oxidation product of a developing agent to release a photographically important compound.

Examples of compounds (including couplers) that react with the oxidation product of a developing agent to release photographically important compound residues include a compound which releases a development inhibitor, such as compounds represented by formulas (I) to (IV) described on page 11 in EP 378,236 A1, compounds represented by formula (I) described on page 7 in EP 436,938 A2, compounds represented by formula (1) described in Japanese Laid-Open Patent Application (JP-A) No. 5-307,248, compounds represented by formulas (I) to (III) described on pages 5 and 6 in EP 440,195 A2, compound-ligand-releasing compounds represented by formula (I) described in claim 1 of Japanese Laid-Open Patent Application (JP-A) No. 6-59,411, and compounds represented by LIG-X described in claim 1 of US 4,555,478.

In the present invention, either a 4-equivalent coupler or a 2-equivalent coupler is selected for use depending on the kind of the developing agent. The use of such a combination can prevent color mixing caused by the movement of the oxidation product of a developing agent between adjacent layers. Examples of the 4-equivalent couplers and the 2-equivalent couplers are described in detail in "Theory of the Photographic Process", 4th ed., by T. H. James, Macmillan, 1977), pages 291-334, pages 354-361 and in Japanese Laid-Open Patent Applications (JP-A) Nos. 58-12,353, 58-149,046, 58-149,047, 59-11,114, 59-124,399, 59-174,835, 59-231,539, 59-231,540, 60-2,951, 60-14,242, 60-23,474 and 60-66,249 in addition to the above-mentioned literatures and patent publications.

The silver halide color photographic light-sensitive material of the present invention requires the use of a base or a base precursor to promote the development of silver and the dye forming reaction. When the silver halide color photographic light-sensitive material is heated alone for heat development, or when the silver halide color photographic light-sensitive material and the processing material are brought together without using any water and then subjected to heat development, it is preferable to use a base precursor described below.

Preferred examples of the base precursor include a compound which is made reactive by heating and releases a base, for example, a salt of an organic Acid and a base capable of decarboxylation by heat, and a compound capable of releasing an amine by an intramolecular nucleophilic substitution reaction, a Lossen rearrangement or a Beckmann rearrangement, and a compound capable of releasing a base by electrolysis or by a complex formation reaction. Examples of the precursor of the former type include a salt of trichloroacetic acid described in British Patent No. 998,949, a salt of α-sulfonylacetic acid proposed as a compound having better stability and described in U.S. Patent No. 4,060,420, a salt of propiolacetic acid described in JP-A No. 59-185,037, a 2-carboxycarboamide derivative described in U.S. Patent No. 4,088,469, a salt of a thermally degradable acid having a basic component which may be not only an organic base but also an alkali metal or an alkaline earth metal (e.g., JP-A No. 59-175,237), a hydroxamcarbamate using a Lossen rearrangement described in JP-A No. 59- 168,440, an aldoxime carbamate which generates a nitrile upon heating, described in JP-A No. 59-157,637.

In addition, a base precursor described in British Patent Specifications Nos. 998,945 and 2,079,480, JP-A No. 59-226,225 and "Known Technologies" No. 5 (issued on March 22, 1991, ASTECH Co., Ltd.), pages 55-86 is also usable.

In addition, as the base precursor in the present invention in which heat evolution is carried out in the presence of a small amount of water, there are also usable a combination of a basic metal compound sparingly soluble in water and a compound capable of reacting with the metal contained in the above basic metal compound using water as a medium to form a complex compound (hereinafter referred to as a complex-forming compound) explained later, described in European Patent Application Laid-Open No. 210,660, U.S. Patent No. 4,740,445 and JP-A No. 62-129,848, and also a compound which forms a base by electrolysis described in JP-A No. 61-232,451. The former type, that is, the above combination, is effective in forming a base. As described in the above publication, from the viewpoint of storage stability of the light-sensitive material, it is preferred that the sparingly water-soluble metal compound and the complex-forming Metal compound contained separately in a light-sensitive silver halide color photographic material and a processing material.

The amount of the base or base precursor to be used in the present invention is normally in the range of 0.1 to 20 g/m², and is preferably 1 to 10 g/m².

Examples of the slightly water-soluble basic metal compound include oxides, hydroxides, basic carbonates and the like of zinc or aluminum. Among these compounds, zinc oxide, zinc hydroxide and basic zinc carbonate are particularly preferred.

As described in JP-A No. 59-174,830, the slightly water-soluble basic metal compound is finely dispersed in a hydrophilic binder. The average grain size of the slightly water-soluble metal compound is in the range of 0.001 to 5 µm, and preferably in the range of 0.01 to 2 µm. The amount of the slightly water-soluble metal compound contained in the silver halide color photographic light-sensitive material is in the range of 0.01 to 8 g/m², and is preferably 0.05 to 5 g/m².

The compound capable of forming a complex with the metal ion of the slightly water-soluble basic metal compound is a compound known as a chelate-forming compound in analytical chemistry and a compound known as a softener for hard water in photographic chemistry. Details of complexes are described in the specifications of the above-mentioned patent publications and also in A. Ringbom, "Complex forming reactions", translated by N. Tanaka et al., Sangyo Tosho Co., Ltd.

The complex-forming compound preferred for use in the present invention is a water-soluble compound, examples of which include an aminopolycarboxylic acid (including a salt thereof) such as ethylenediaminetetraacetic acid, nitrilotriacetic acid and diethylenetriaminepentaacetic acid, an aminophosphonic acid (a salt) such as aminotris(methylenephosphonic) acid and ethylenediaminetetramethylenephosphonic acid, and a pyridinecarboxylic acid (a salt) such as 2-picolinic acid, Pyridine-2,6-dicarboxylic acid and 5-ethyl-2-picolinic acid. Among these compounds, a pyridinecarboxylic acid (a salt) is particularly preferred.

In the present invention, it is preferable to use the above-mentioned complex-forming compound in the form of a salt formed by neutralizing the complex-forming compound with a base. Particularly preferable salts are a salt with an organic base such as a guanidine, an amidine or a tetraalkylammonium hydroxide, and a salt with an alkali metal such as sodium, potassium or lithium. Alternatively, combinations of these salts may also be used. Preferred examples of the complex-forming compounds are described in, for example, JP-A No. 62-129,848 and European Patent Application Laid-Open No. 210,660 A2. The amount of the complex-forming compound present in the silver halide color photographic light-sensitive material is in the range of 0.1 to 20 g/m², and is preferably 0.1 to 10 g/m².

The binder for a constituting layer of the silver halide color photographic light-sensitive material is preferably a hydrophilic material, examples of which include those described in the above-mentioned Research Disclosure and Japanese Patent Laid-Open (JP-A) No. 64-13,546, pages 71-75. More specifically, the binder is preferably a transparent or translucent hydrophilic material, examples of which include a naturally occurring compound such as a protein including gelatin and a gelatin derivative; and a polysaccharide including a cellulose derivative, starch, gum arabic, dextran and pullulan, and a synthetic polymer such as polyvinyl alcohol, polyvinylpyrrolidone and acrylamide polymer. Also usable as the binder is a highly water-absorbent polymer described in U.S. Patent No. 4,960,681 and Japanese Patent Laid-Open (JP-A) No. 62-245,260, for example, a homopolymer composed of a vinyl monomer having -COOM or -SO₃M (M represents a hydrogen atom or an alkali metal) or a copolymer obtained by a combination of these monomers, or obtained by a combination of at least one of these monomers and other monomer(s) such as sodium methacrylate and ammonium methacrylate, SUMIKAGEL L-5H manufactured by Sumitomo Chemical Co., Ltd. These binders may be used singly or in a combination of two or more of them. In particular, a combination of gelatin and one of the above-mentioned non-gelatin binders is preferred. Depending on the purposes, a lime-treated gelatin, an acid-treated gelatin and a decalcified gelatin which has been subjected to a decalcification process to reduce the calcium content may be used. Alternatively, a combination of these treated gelatin substances may be used.

In the present invention, the applied weight of the binder is preferably 1 to 20 g/m², and more preferably 2 to 10 g/m².

Hydrophobic additives such as the coupler, developing agent and non-diffusible reducing agent described above can be incorporated into a layer of a silver halide color photographic light-sensitive material by a known method such as the method described in U.S. Patent No. 2,322,027. In this case, an organic solvent having a high boiling point described in U.S. Patent Nos. 4,555,470, 4,536,466, 4,536,467, 4,587,206, 4,555,476 and 5,599,296 and Japanese Patent Publication (JP-B) No. 3-62,256 may be used, if necessary, together with an organic solvent having a lower boiling point in the range of 50 to 160°C. Besides these color-forming compounds, non-diffusible reducing agents and organic solvents having a high boiling point may be used in a combination of two or more of them.

The amount of the organic solvent having a high boiling point is 10 g or less, preferably 5 g or less, and more preferably in the range of 0.1 to 1 g, based on 1 g of the hydrophobic additives to be used. The amount of the organic solvent having a high boiling point is 1 cm³ or less, preferably 0.5 cm³ or less, more preferably 0.3 cm³ or less, based on 1 g of the binder.

Examples of usable methods for introducing a hydrophobic additive into the layer of a photosensitive material include a dispersion method using a polymer as described in Japanese Patent Publication (JP-B) No. 51-39,853 and Japanese Laid-Open Publication (JP-A) No. 51-59,943, and a method wherein a hydrophobic additive incorporated in a dispersion of fine grains is added to the layer as described in Japanese Patent Application Laid-Open (JP-A) No. 62-30,242.

In addition to the above methods, in the case where the hydrophobic additive is a substantially water-insoluble compound, the hydrophobic compound may be dispersed in a binder.

When a hydrophobic compound is dispersed to form a hydrophilic colloidal dispersion, a variety of surfactants can be used. For example, surfactants described in Japanese Laid-Open Patent Application (JP-A) No. 59-157,636, pages 37-38 and the above-mentioned Research Disclosure can be used. In addition, a phosphoric ester type surfactant described in Japanese Laid-Open Patent Application (JP-A) Nos. 7-56,267 and 7-228,589 and German Laid-Open Patent Application No. 1,932,299 A can also be used in the light-sensitive material of the present invention.

In the present invention, a color reproduction according to a color subtraction method can be basically used for producing a silver halide color photographic light-sensitive material to be used for reproducing an original scene as a color image. That is, the color information of the original scene can be recorded by means of a color negative film having at least three photosensitive layers having a sensitivity to the blue, green and red wavelength ranges of light, respectively, and incorporated with a color coupler capable of producing a yellow, magenta or cyan dye as a complementary color of the photosensitive wavelength range of the layer. Through the color image thus obtained, a color photographic paper having a wavelength sensitivity to hue relationship identical to that of the color negative film is optically exposed to thereby reproduce the original scene. Alternatively, it is also possible to reproduce a color image for pleasure by reading out the information of the color image obtained by taking a photograph of an original scene by means of a scanning device.

The photosensitive material of the present invention may contain three or more photosensitive layers, each having a sensitivity to light of a wavelength different from the other two. In addition, the relationship between the sensitive wavelength range and the hue of the layer may be different from the complementary color relationship described above. In this case, it is possible to reproduce the original color information by image processing, e.g., color inversion, of the image information read out as described above.

Preferably, the silver halide color photosensitive material of the present invention has at least two silver halide emulsions having spectral sensitivity in the same wavelength region, and they have different mean grain projected areas. The term "spectral sensitivity in the same wavelength region" as used herein means sensitivity to substantially the same wavelength region. Therefore, emulsions having slightly different distributions of spectral sensitivity but having photosensitive regions that largely overlap with each other are regarded as emulsions having photosensitivity in the same wavelength region.

In the present invention, a plurality of emulsions having spectral sensitivity in the same wavelength range and different mean grain projected area may be used separately in different photosensitive layers, or the plurality of emulsions may be mixed and incorporated in the same photosensitive layer.

When these emulsions are contained in separate photosensitive layers, the color coupler to be combined therewith preferably has the same hue, however, couplers forming a color in different hues may be mixed to give different colored hues in the respective photosensitive layers, or couplers having different hue absorption profiles may be used in the respective photosensitive layers.

In the present invention, these emulsions with spectral sensitivity in the same wavelength range must be applied in such a construction that an emulsion having a larger mean grain projected area has a ratio of silver halide grain numbers per unit area of the photosensitive material larger than the ratio of the values obtained by dividing the coated silver amount of the emulsion by 3/2 power of the mean grain projected area. By the above-described construction, it is possible to obtain an image having excellent graininess even when the photosensitive material is developed at a high temperature. In addition, it is also possible to achieve high developability and a wide latitude for exposure.

In a color negative conventionally used in photography, in order to achieve a desired level of graininess, a silver halide emulsion has been improved, and a so-called DIR coupler which releases a compound capable of inhibiting development by reacting with the oxidation product of a developing agent has been used. The light-sensitive material according to the present invention gives an excellent level of graininess even when a DIR coupler is not used in the light-sensitive material. When the light-sensitive material according to the present invention contains DIR couplers, the graininess is further improved.

A non-light-sensitive layer such as a protective layer, a substratum, an interlayer, a yellow filter layer and/or an antihalation layer may be formed between the light-sensitive photographic layers containing a light-sensitive silver halide emulsion of the silver halide color photographic light-sensitive material and/or as an overcoat layer and/or as an undercoat layer thereof. Further, a supplementary layer such as a backing layer may be formed on the back side of the support which is opposite to the side on which the light-sensitive photographic layer is formed. More specifically, it is possible to form on the support various layers including the above-mentioned construction, a substrate described in U.S. Patent No. 5,051,335, an intermediate layer containing a solid pigment described in Japanese Patent Laid-Open (JP-A) Nos. 1-167,838 and 61-20,943, an intermediate layer containing a reducing agent or a DIR compound described in Japanese Patent Laid-Open (JP-A) Nos. 1-120,553, 5-34,884 and 2-64,634, an intermediate layer containing an electron transport layer described in U.S. Patent 5,017,454 and 5,139,919 and Japanese Patent Application Laid-Open (JP-A) No. 2,235,044, and a protective layer containing a reducing agent described in Japanese Patent Application Laid-Open (JP-A) No. 4,249,245, as well as a combination of two or more of these layers.

A dye that can be used in a yellow filter layer or in an antihalation layer is preferably a dye that loses its color or is removed at the time of development so that it has no influence on the density of the image after the process.

That the dye present in the yellow filter layer or in the antihalation layer loses its color or is removed at the time of development means that the amount of the dye remaining after the process is less than 1/3, preferably less than 1/10, of the amount of the dye present before the process. This can be achieved by a phenomenon in which the component of the dye is leached out of the light-sensitive material or transferred into the processing material at the time of development, or by a phenomenon in which the component of the dye undergoes a reaction and becomes a colorless compound at the time of development.

In the silver halide color photographic light-sensitive material of the present invention, a known dye can be used. For example, usable dyes include a dye which is soluble in an alkaline solution of a developer and a dye which becomes colorless as a result of reaction with a component of the developing solution, sulfite ion, a developing agent or an alkali.

Concrete examples of the dyes include the dye described in European Patent Application EP 549,489 A and the dye ExF 2-6 described in Japanese Patent Application Laid-Open (JP-A) No. 7-152,129. A dye dispersed in fine solid particles described in Japanese Patent Application Laid-Open (JP-A) No. 8-101,487 may also be used. Although this dye can also be used in the case where the silver halide color photographic light-sensitive material is developed with a processing solution, this dye is particularly suitable for the case where the silver halide color photographic light-sensitive material Silver halide material is subjected to heat development using a processing material described later.

Further, it is also possible to fix a dye to a mordant and a binder. In this case, the mordant and the dye may be those known in the field of photography. Examples of the mordants include those described in U.S. Patent No. 4,500,626, columns 58-59, and Japanese Laid-Open Patent Applications (JP-A) Nos. 61-88,256, pages 32-41, 62-244,043, and 62-244,036.

Furthermore, it is also possible to use a reducing agent and a compound that reacts with the reducing agent to release a diffusible dye, so that the alkali formed at the time of development causes a reaction to release a mobile dye, which is removed either by being dissolved in the processing solution or by being transferred into the processing material. Examples of these compounds and reducing agents are described in U.S. Patent Nos. 4,559,290 and 4,783,369, European Patent Publication No. 220,746 A2, JIII Journal of Technical Disclosure No. 87-6,119 and Japanese Laid-Open Publication (JP-A) No. 8-101,487, paragraph 0080-0081.

A leuco dye which becomes colorless can also be used in the light-sensitive material of the present invention. For example, Japanese Laid-Open Patent Publication (JP-A) No. 1-150,132 describes a silver halide light-sensitive material containing a leuco dye which previously obtains a color by means of a metal salt of an organic acid as a color developer. Since a complex of a leuco dye and a developer undergoes a reaction by heat or reacts with an alkali to become colorless, the use of the combination of the leuco dye and a color developer in the light-sensitive material of the present invention is desirable when the light-sensitive material of the present invention is to be subjected to heat development.

In the present invention, a known leuco dye can be used, examples of which are given in Moriga and Yoshida, "Senryo to Yakuhin (Dyeants and Chemicals)", Vol. 9, page 84, Association of Chemical Products", "Shinban Senryo Binran (New Dye Manual)", page 242, Maruzen Co., Ltd. (1970), R. Garner, "Reports on the Progress of Applied Chemistry", vol. 56, page 199 (1971), "Senryo to Yakuhin (Dye Materials and Chemicals)", vol. 19, page 230, Association of Chemical Products (1974), "Shikizai (Color Materials)", vol. 62, page 288 (1989) and "Senryo Kogyo (Dye Industry)", vol. 32, page 208. Preferred color developers are a metal salt of an organic acid in addition to acidic clay developers and a phenol/formaldehyde resin. Among metal salts of organic acids, metal salts of salicylic acids, a metal salt of a phenol/salicylic acid/formaldehyde resin, a rhodane salt and a metal salt of Xanthogenic acid is preferred. Among the metals, zinc is particularly preferred. An oil-soluble zinc salicylate described in U.S. Patent Nos. 3,864,146 and 4,046,941 and Japanese Patent Publication (JP-B) No. 52-1,327 can also be used as a color developer.

The silver halide color light-sensitive material in the present invention may contain a compound which activates development and stabilizes the image. Preferred examples of these compounds are described in U.S. Patent 4,500,626, columns 51-52.

An organic metal salt can be used as an oxidizing agent together with a light-sensitive silver halide in the present invention. Among these organic metal salts, an organic silver salt is particularly preferred.

Examples of the organic compounds that can be used to prepare the above-mentioned organic silver salts serving as oxidizing agents include benzotriazoles, fatty acids and other compounds described in U.S. Patent 4,500,626, columns 52-53. The silver acetylide described in U.S. Patent 4,775,613 is also usable. These silver salts can be used alone or in a combination of two or more of them.

The above-mentioned organic silver salt may be used in an amount in the range of 0.01 to 10 mol, and preferably 0.01 to 1 mol, based on 1 mol of the photosensitive silver halide. The total applied weight of the photosensitive silver halide and the organic silver salt is in the Range from 0.05 to 10 g/m² and preferably from 0.1 to 4 g/m², based on the weight of silver.

The photosensitive material of the present invention is preferably cured by means of a hardener.

Examples of the hardener include those described in U.S. Patent Nos. 4,678,739, column 41 and 4,791,042 and Japanese Patent Laid-Open (JP-A) Nos. 59-116,655, 62-245,261, 61-18,942 and 4-218,044. More specifically, examples of these hardeners include an aldehyde (e.g., formaldehyde), an aziridine, an epoxy compound, a vinyl sulfone (e.g., N,N'-ethylene-bis(vinylsulfonylacetamide)ethane), an N-methylol compound (e.g., dimethylol urea), boric acid, metaboric acid and a polymeric compound (e.g., a compound described in Japanese Patent Laid-Open (JP-A) No. 62-234,157).

The amount of hardener added is in the range of 0.001 g to 1 g, preferably 0.005 to 0.5 g, based on 1 g of the hydrophilic binder.

The silver halide color photographic light-sensitive material may contain both an antifoggant or a photographic stabilizer and a precursor thereof, examples of which include the compounds described in the above-mentioned Research Disclosure, U.S. Patent Nos. 5,089,378, 4,500,627 and 4,614,702, Japanese Patent Laid-Open (JP-A) No. 64-13,564, pages 7-9, pages 57-71 and pages 81-97, U.S. Patent Nos. 4,775,610, 4,626,500 and 4,983,494, Japanese Patent Laid-Open (JP-A) Nos. 62-174,747, 62-239,148, 1-150,135, 2,110,557 and 2-178,650 and in RD 17,643 (1978), pages 24-25.

The amount of these compounds added is preferably in the range of 5 x 10⁻⁶ to 1 x 10⁻¹ mol, more preferably 1 x 10⁻⁶ to 1 x 10⁻² mol, based on 1 mol of silver.

A general thermal process of a light-sensitive silver halide color photographic material is known in the art. For example, a light-sensitive Material for heat development and a heat development method described in "Syashinkogaku no kiso (Fundamentals of Photographic Engineering)", pages 553-555, Corona Co., Ltd. (1970), "Eizojoho (Image Information)" (April 1978), page 40, "Neblett's Handbook of Photography and Reprography", 7th ed. (Van Nostrand and Reinhold Company), pages 32-33, U.S. Patent Nos. 3,152,904, 3,301,678, 3,392,020 and 3,457,075, British Patent Nos. 1,131,108 and 1,167,777 and Research Disclosure (June 1978), pages 9-15 (RD-17,029).

The light-sensitive material of the present invention can be developed by an activator method or a processing solution containing a developing agent or a base.

The activator process means a developing process in which a light-sensitive material containing a color developing agent is treated with a processing solution containing no color developing agent. A feature of the activator process is that the processing solution for the process does not contain a color developing agent contained in an ordinary developing solution. The processing solution for the activator process may contain components such as an alkali and a co-developing agent. Examples of the activator processes are described in published literatures such as European Patent Publications Nos. 545,491 A1 and 565,165 A1.

Methods for developing a light-sensitive material using a processing solution containing a developing agent and a base are described in RD No. 17,643, pages 28-29, 18,716, page 651, left column to right column, and 307,105, pages 880-881.

Details of the processing material and processing method to be used in the heat development method of the present invention are listed below.

The light-sensitive material of the present invention may contain a thermal solvent to facilitate heat development, examples of which polar organic compounds described in U.S. Patent Nos. 3,347,675 and 3,667,959. Examples of such compounds include amide derivatives (e.g., benzamide), urea derivatives (e.g., methylurea and ethyleneurea), sulfonamide derivatives (e.g., compounds described in Japanese Patent Publication (JP-B) Nos. 1-40,974 and 4-13,701), polyol compounds (e.g., a sorbitol and a polyethylene glycol).

When the thermal solvent is insoluble in water, the thermal solvent is preferably used as a solid dispersion. Depending on the purposes, the thermal solvent may be contained in each photosensitive layer and non-photosensitive layer.

The amount of thermal solvent added is in the range of 10 to 500 wt.%, preferably 20 to 300 wt.%, based on the weight of the binder present in the layer to which the thermal solvent is to be added.

Although the heating temperature of the heat development process is in the range of 50 to 250°C, the temperature is preferably in the range of 60 to 150°C. The processing material may have other functions, such as a function of excluding the air at the time of heat development, a function of preventing the evaporation of the components of the photosensitive material, a function of supplying a material other than the base to the photosensitive material, and a function of removing a component of the photosensitive material which becomes unnecessary after the development process (e.g., YF dye and AH dye) or an unnecessary component which is formed during the development process. The support and the binder for the processing material may be the same as those for the photosensitive material.

The processing material may contain a mordant for removing the dye as described above or for another purpose. The mordant may be any of those known in the field of photography, examples of which include the mordants described in U.S. Patent No. 4,500,626, columns 58-59 and Japanese Laid-Open Patent Application (JP-A) No. 61-88,256, pages 32- 41, 62-244,043 and 62-244,036. Furthermore, the processing material may contain a polymeric compound as a dye acceptor described in U.S. Patent No. 4,463,079 or the above-mentioned thermal solvent.

The processing layer of the processing material contains a base and/or a base precursor. The base may be either an organic base or an inorganic base. The base precursor may be any of those described hereinbefore. The amount of the base or the base precursor to be used in the present invention is in the range of 0.1 to 20 g/m², preferably 1 to 10 g/m².

At the time when the light-sensitive material of the present invention undergoes a heat development process using the processing material, a small amount of water is used for such purposes as accelerating the development, accelerating the transfer of the processing material or accelerating the diffusion of unnecessary substances, as described in U.S. Patent Nos. 4,704,245 and 4,470,445 and Japanese Patent Laid-Open (JP-A) No. 61-238,056. Such compounds as an inorganic salt of an alkali metal, an organic base, a solvent having a low boiling point, a surfactant, an antifoggant, a compound for forming a complex with a metal salt sparingly soluble in water, an antimold agent and an antibacterial agent may be added to the water.

The water has no particular specification, and examples of the water include ion-exchange water, distilled water, tap water, spring water and mineral water. In the heat developing apparatus using the photosensitive material of the present invention and the processing material, the waste water may be discharged without reuse, or it may be recycled for repeated use. When recycled water is used, the used water accumulates the components leached from the materials during repeated use. Further, the apparatus and the water described in Japanese Patent Application Laid-Open (JP-A) Nos. 63-144,354, 63-144,355, 62-38,460 and 3-210,555 can be used in the present invention.

Water may be added to the photosensitive material or the processing material or to both materials. The amount of water to be added is in the range of 1/10 to the equivalent of an amount required for maximum swelling of the total coated layers of the photosensitive material and the processing material.

Preferred examples of methods for supplying water to these materials include the methods described in Japanese Patent Application Laid-Open (JP-A) Nos. 62-253,159, page 5 and 63-85,544. Further, water in the form of microcapsules or hydrates may be previously incorporated into the photosensitive material or the processing material or both of them.

The temperature of the water to be supplied can be in the range of 30 to 60ºC as described, for example, in Japanese Patent Application Laid-Open (JP-A) No. 63-85,544.

When heat development of the photosensitive material is carried out in the presence of a small amount of water, it is effective to employ a method in which a combination of a sparingly water-soluble basic metal compound and a complex-forming compound is used so that a base is formed, as described in European Patent Application Laid-Open No. 210,660 and U.S. Patent No. 4,470,455. In this case, from the viewpoint of storage stability of the raw materials, it is desirable to incorporate the sparingly water-soluble basic metal compound into the photosensitive material and to incorporate the complex-forming compound into the processing material.

Examples of the heating method in the developing process include a method in which the photosensitive material is brought into contact with a heated block or a heated plate, a method in which the photosensitive material is brought into contact with such an object as a hot plate, a hot printing device, a hot roller, a hot drum, a heater with a halogen lamp and a heater with an infrared lamp or a far infrared lamp, and a method in which the photosensitive material is passed through a hot atmosphere.

As for the method of arranging the photosensitive material and the processing material face to face so that the photosensitive layer and the processing layer face each other, the methods described in Japanese Patent Application Laid-Open (JP-A) Nos. 62-253-159 and 61-147,244, page 27 can be used.

For processing the photosensitive material and the processing material of the present invention, any known heat development device can be used. Preferred examples of the device include the devices described in Japanese Laid-Open Patent Application Nos. 59-75,247, 59-177,547, 59-181,353 and 60-18,951, Japanese Utility Model Application Laid-Open (JP-U) No. 62-25,944 and Japanese Laid-Open Patent Application (JP-A) Nos. 6-130,509, 6-95,338, 6-95,267, 8-29,955 and 8-29,954.

In addition, commercially available devices such as "Pictrostat" 100, 200, 300, 330 and 50 and "Pictrography" 3000 and 2000 manufactured by Fuji Photo Film Co., Ltd. can be used in the present invention.

The photosensitive material and/or the processing material to be used in the present invention may have an electrically conductive heat generating layer as a heating means for heat development. For example, a heat generating layer described in Japanese Patent Application Laid-Open (JP-A) No. 61-145,544 may be used.

Although in the present invention the image information can be read out from the light-sensitive material without removing the silver formed by development and the undeveloped silver halide, it can be read out after removing the silver or silver halide. In the latter case, the silver or silver halide can be removed simultaneously with or after development.

In order to remove the developed silver from the light-sensitive material simultaneously with development or to complex or solubilize the silver halide, the processing material may contain a silver oxidizing agent or a rehalogenating agent which serves as a bleaching agent and a solvent for the silver halide which serves as a fixing agent so that these reactions proceed at the time of heat development.

Further, after the development process, a second processing material containing a silver oxidizing agent or rehalogenating agent or a solvent for silver halide and the light-sensitive material may be placed face to face so that removal of the developed silver or complexing or solubilization of the silver halide can be carried out.

In the present invention, so far as the above-mentioned process does not give any adverse effects on the readout of the image information after development, it is preferred that the light-sensitive material is subjected to the above-mentioned process. Since the undeveloped silver halide causes considerable fog in gelatin films to the extent that the background density increases, it is preferred to reduce the fog by using the above-mentioned complexing agent or to solubilize the silver halide so that all or part of the silver halide is removed from the film.

From the viewpoint of reducing fog, it is preferable to use tabular silver halide grains having a high aspect ratio or tabular silver halide grains having a high silver chloride content as described in the present invention.

In the present invention, a processing material may contain a commonly used silver bleach. Examples of a silver bleach are described in U.S. Patent Nos. 1,315,464 and 1,946,640 and in "Photographic Chemistry," Vol. 2, Chapter 30, Foundation Press, London, England. These bleaches effectively oxidize a silver image to make it soluble. Examples of usable silver bleaches include an alkali metal salt of dichromic acid and an alkali metal ferricyanide.

Preferred bleaching agents are a water-soluble compound, examples of which include ninhydrin, indandione, hexaketocyclohexane, 2,4-dinitrobenzoic acid, benzoquinone, benzenesulfonic acid and 2,5-dinitrobenzoic acid. The bleaching agents also include an organic complex of a metal such as a ferric salt of cyclohexyldialkylaminetetraacetic acid, a ferric salt of ethylenediaminetetraacetic acid and a ferric salt of citric acid. The fixing agent may be a solvent for silver halide (i.e., a solvent capable of dissolving silver halide) which can be used in the processing material for developing the light-sensitive material (the first processing material). The binder, carrier and other additives usable in the second processing material may also be the same substances as those usable in the first processing material.

The amount of the bleaching agent to be added should be determined depending on the amount of silver contained in the photosensitive material and is in the range of 0.01 to 10 times, preferably 0.1 to 3 times, and more preferably 0.1 to 2 times the amount (mol) of silver contained in the photosensitive material per unit area.

The solvent for silver halide may be a known compound, examples of which include thiosulfates such as sodium thiosulfate and ammonium thiosulfate, sulfites such as sodium sulfite and sodium hydrogen sulfite, thiocyanates such as potassium thiocyanate and ammonium thiocyanate, thioethers such as 1,8-di-3,6-dithiaoctane, 2,2'-thiodiethanol, 6,9-dioxa-3,12-dithiatetradecane-1,14-diol as described in Japanese Patent Publication (JP-B) No. 47-11,386, a compound having a 5- or 6-membered imido ring such as urasil and hydantoin as described in Japanese Patent Laid-Open (JP-A) No. 8-179,458, and a compound represented by the following general formula (V) as described in Japanese Patent Laid-Open (JP-A) No. 53-144,319. A mesoionthiolate compound of trimethyltriazolium thiolate described in "Analytica Chemica Acta", vol., 248, pages 604 to 614 (1991) is also a preferred compound. A compound described in Japanese Patent Application Laid-Open (JP-A) No. 8-69,097, which is capable of stabilizing a silver halide to fix, can also be used as a solvent for the silver halide.

General formula (V)

N(R⁹)(R¹⁰)-C(=S)-X-R¹¹

wherein X represents a sulfur atom or an oxygen atom. R⁹ and R¹⁰, which may be the same or different, each represents an aliphatic group, an aryl group, a heterocyclic group or an amino group. R¹¹ represents an aliphatic group or an aryl group. R⁹ and R¹⁰ or R¹⁰ and R¹¹ may be bonded to each other to form a 5-membered or a 6-membered heterocyclic ring. The solvents for the silver halide described above may be used alone or in a combination of two or more of them.

Among the compounds described above, a compound having a 5-membered or 6-membered imido ring such as urasil or hydantoin is particularly preferred.

The content of the total amount of the solvent for silver halide in the processing layer is in the range of 0.01 to 100 mmol/m², preferably 0.1 to 50 mmol/m², and more preferably 10 to 50 mmol/m². The total amount of the solvent for silver halide in the photosensitive material is in the range of 1/20 to 20 times, preferably 1/10 to 10 times, and more preferably 1/3 to 3 times the amount (mol) of silver present in the photosensitive material. When the solvent for silver halide is used, it may be added to a solvent such as water, methanol, ethanol, acetone, dimethylformamide or methylpropyl glycol, or to an alkaline or acidic aqueous solution, or else a fine solid dispersion containing the solvent for silver halide may be added to a coating solution.

Alternatively, the processing material may contain a physical development nucleus and the silver halide solvent, so that the silver halide solvent solubilizes the silver halide contained in the light-sensitive material simultaneously with development, and so that the physical development nucleus soluble silver halide diffused from the photosensitive material to convert it into physically developed silver to be fixed to a processing layer. In the present invention, any physical development nucleus known per se can be used. Examples of the physical development nucleus include colloidal grains of a heavy metal such as zinc, mercury, lead, cadmium, iron, chromium, nickel, tin, cobalt, copper and ruthenium, a noble metal such as palladium, platinum, silver and gold, a chalcogen compound composed of the above components and a substance such as sulfuric acid, selenium or tellurium. These physical development nucleus substances are obtained by reducing a corresponding metal ion using a reducing agent such as ascorbic acid, sodium borohydride or hydroquinone to prepare a colloidal dispersion of metal, or by mixing a metal ion with a solution containing a soluble sulfide, selenide or telluride to prepare a colloidal dispersion of insoluble metal sulfide, metal selenide or metal telluride, respectively. These colloidal grains are preferably formed in a hydrophilic binder such as gelatin. The method for preparing colloidal silver grains is described, for example, in U.S. Patent No. 2,688,601. If necessary, in preparing the colloidal silver, a salt removal process may be carried out as is known in a method for preparing a silver halide emulsion in which excess salt is removed.

The grain diameters of these physical development nuclei are preferably in the range of 2 to 200 nm.

The physical development nuclei are normally present in the processing layer in an amount in the range of 10⁻³ to 100 mg/m², preferably from 10⁻² to 10 mg/m².

Although the physical development nucleus can be prepared separately from a coating solution and the physical development nuclei can be added thereafter to the coating solution, the physical development nucleus can be prepared, for example, by the reaction between silver nitrate and sodium sulfide or between gold chloride and a reducing agent in a coating solution containing a hydrophilic binder.

Silver, silver sulfide or palladium sulfide is preferably used as a physical development nucleus. When the physically developed silver transferred to a processing material is used as an image, it is preferred to use palladium sulfide or silver sulfide because they have low fogging and high Dmax (maximum density) values.

Both the first processing material and the second processing material may have at least one polymerizable timing layer. The polymerizable timing layer may temporarily delay the bleaching and fixing reaction until the desired reaction between the silver halide, a dye-forming compound and a developing agent is substantially complete. The timing layer may comprise gelatin, polyvinyl alcohol or a vinyl alcohol/vinyl acetate copolymer. This layer may be a barrier timing layer as described in U.S. Patent Nos. 4,056,394, 4,061,496 and 4,229,516.

The film thickness of the timing layer is in the range of 5 to 50 µm, preferably 10 to 30 µm.

According to the present invention, the photosensitive material is bleached and fixed after its exposure using the second processing material. That is, the method comprises supplying water in an amount in a range of 1/10 to the equivalent of an amount required for maximum swelling of the sum of the photosensitive material layer and the second processing material layer excluding the respective back layers to the photosensitive material or to the second processing material, arranging the photosensitive material and the second processing material so that the photosensitive layer and the processing layer face each other, and then heating these layers at a temperature in the range of 40 to 100°C for 5 to 60 seconds.

As for the amount of water, the type of water, the method of supplying water and the method of arranging the photosensitive material and the second processing material, As far as front to front is concerned, the same as those used in the case of the first processing material can be used.

More specifically, in the present invention, the second processing material described in Japanese Laid-Open (JP-A) No. 59-136,733, U.S. Patent No. 4,124,398 and Japanese Laid-Open (JP-A) No. 55-28,098 can be used.

For such purposes as improving coatability, improving releasability, improving slipperiness, preventing electrostatic charge and accelerating the development reaction, a surfactant may be added to the photosensitive material. Examples of the surfactants include those described in "Known Technologies" No. 5 (published on March 22, 1991, AZTEC Co., Ltd.), pages 136-138 and Japanese Laid-Open Patent Applications (JP-A) Nos. 62-173,463 and 62-183,457.

For such purposes as preventing slippage, preventing electrostatic charge and improving releasability, an organic fluorine-containing compound may be added to the photosensitive material. Typical examples of the organic fluorine-containing compounds include a fluorine-containing surfactant and a hydrophobic fluorine-containing compound such as an oily fluorine-containing compound such as fluorocarbon oil, a solid fluorine-containing resin such as tetrafluoroethylene described in Japanese Patent Publication (JP-B) No. 57-9,053, columns 8-17 and Japanese Laid-Open Publication (JP-A) Nos. 61-20,944 and 62-135,826.

Preferably, the photosensitive material has a certain slipperiness. For this purpose, the photosensitive material may contain a lubricant. It is preferred that a lubricant is contained in both the photosensitive layer and the backing layer. A preferred value of the slipperiness is indicated by a coefficient of dynamic friction in the range of 0.01 to 0.25, which represents a measurement value determined in a test which examines the slip of the photosensitive material at a speed of 60 cm/minute against stainless steel balls having a diameter of 5 mm (25°C, 50% relative humidity). humidity). Here, even in the case of the photosensitive layer, essentially the same value can be obtained.

Examples of usable lubricants include polyorganosiloxanes, higher aliphatic acid amides, metal salts of higher fatty acid, and esters made from higher fatty acids and higher alcohols. Examples of the polyorganosiloxanes include polydimethylsiloxane, polydiethylsiloxane, polystyrylmethylsiloxane, and polymethylphenylsiloxane. Polydimethylsiloxane and an ester having a long alkyl chain are particularly preferred. The layer to which the lubricant is added is preferably the outermost photosensitive layer or the back layer.

In the present invention, it is preferable to use an antistatic agent. As the antistatic agent, polymers containing carboxylic acid, carboxylic acid salt or sulfonic acid salt, cationic polymers and ionic surfactants can be used.

The most preferred antistatic agent is grains of at least one type of crystalline metal oxide having grain sizes in the range of 0.001 to 1.0 µm selected from the group consisting of ZnO, TiO₂, SnO₂, Al₂O₃, In₂O₃, SiO₂, MgO, BaO, MoO₃ and V₂O₅ and having a volume resistivity of 10⁷ Ω·cm or less, preferably 10⁵ Ω·cm or less, or grains of a complex oxide thereof, for example, a complex of an element such as Sb, P, B, In, S, Si and C and the above-mentioned metal oxide. The amount of the antistatic agent present in the photosensitive material is preferably in the range of 5 to 500 mg/m², more preferably in the range of 10 to 350 mg/m². The ratio of the electrically conductive crystalline oxide or the complex oxide thereof to a binder is preferably in the range of 1/300 to 100/1, more preferably 1/100 to 100/5.

The silver halide color light-sensitive material (including back layers) may contain a polymer latex to improve physical film properties such as dimensional stability, prevention of curling, prevention of sticking, prevention of film breakage and prevention of pressure-induced sensitization or desensitization. Any and all polymer latexes described in Japanese Patent Application Laid-Open Nos. 1-644-234 and 1-644-234 may be used in the present invention. (JP-A) Nos. 62-245,258, 62-136,648 and 62-110,066. In particular, the use of a polymer latex having a low glass transition point (40°C or less) in the mordant layer of the processing material can prevent the mordant layer from breaking, while the use of a polymer latex having a high glass transition point in the back layer of the processing material can prevent the curling.

Preferably, the silver halide color photosensitive material of the present invention contains a matting agent. Although the matting agent may be added to either the photosensitive layer or the back layer, it is particularly preferred that the matting agent is added to the outermost layer on the same side of the support where the photosensitive layer is provided. Although the matting agent may be soluble or insoluble in a processing solution, in the present invention it is preferred to use a combination of a soluble matting agent and an insoluble matting agent. An example of such a combination of matting agents includes grains of polymethyl methacrylate, poly(methyl methacrylate/methacrylic acid) (in a molar ratio of 9/1 or 5/5) and polystyrene. The matting agent has grain diameters preferably in the range of 0.8 to 10 µm and preferably has a narrow range of grain diameter distribution. It is preferable that 90% or more of the total number of grains have a diameter falling within the range of 0.9 to 1.1 times the average grain diameter. Besides, in order to increase the matting effect, it is also preferable to use fine grains having a grain diameter of 0.8 µm or less together with the matting agent having the above-mentioned grain diameter. Examples of fine grains include grains of polymethyl methacrylate (0.2 µm), grains of poly(methyl methacrylate/methacrylic acid) (in a molar ratio of 9/1, 0.3 µm), grains of polystyrene (0.25 µm), and grains of colloidal silica (0.03 µm).

Concrete examples of the matting agent are described in Japanese Patent Application Laid-Open (JP-A) No. 61-88,256, page 29. Other examples of the matting agent are such materials as benzoguanamine resin beads, polycarbonate beads and AS resin beads, all of which are described in Japanese Patent Application Laid-Open (JP-A) Nos. 63-274,944 and 63-274,952. Furthermore, the compounds described in the above Research Disclosure may be used as the matting agent.

In the present invention, a support for the photosensitive material and the processing material must be capable of withstanding the processing temperature. Generally, examples of the support are paper, a synthetic polymer (film) as described in "Syashinkogaku no kiso - Ginen Syashin Hen (Fundamentals of Photographic Engineering - Silver Salt Photography Section)", pages 223-240, published by Photographic Society of Japan, Corona Co., Ltd., 1979. Specific examples of the support include polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyvinyl chloride, polystyrene, polypropylene, polyimide and cellulose (e.g. triacetyl cellulose).

These materials may be used alone. Furthermore, a support may be used in which a synthetic polymer such as polyethylene may be laminated to one side or both sides of paper.

Other supports that can be used in the present invention include those described in Japanese Patent Application Laid-Open (JP-A) Nos. 62-253,159, pages 29-31, 1-161,236, pages 14-17, 63-316,848, 2-22,651 and 3,56,955 and in US Patent No. 5,001,033.

Where resistance to heat and rolling is mandatory, preferred examples of the supports are those described in Japanese Laid-Open Patent Applications (JP-A) Nos. 6-41,281, 6-43,581, 6-51,426, 6-51,437 and 6-51,442 and Japanese Laid-Open Patent Applications (JP-A) Nos. 6-82,961, 6-82,960, 6-123,937, 6-82,959, 6-67,346, 6-266,050, 6-202,277, 6-175,282, 6-118,561, 7-219,129 and 7-219,144 and in U.S. Pat. No. 5,326,689.

Also preferred is a carrier made mainly of a styrene-based polymer having a syndiotactic structure.

In order to bond the photographic layer to the support, it is preferred that the support is surface treated. Examples of the surface methods include a chemical method, a mechanical method, a corona discharge method, a A flame method, an ultraviolet ray method, a high frequency wave method, a glow discharge method, an activated plasma method, a laser method, a mixed acid method, and an ozone oxidation method. Among these surface methods, an ultraviolet irradiation method, a flame method, a corona discharge method, and a glow discharge method are particularly preferred.

A substrate may comprise a single layer or two or more layers. Examples of the binder for the substrate include a copolymer made from a monomer selected from the group consisting of vinyl chloride, vinylidene chloride, butadiene, methacrylic acid, acrylic acid, itaconic acid, maleic anhydride, polyethyleneimine, an epoxy resin, grafted gelatin, nitrocellulose and gelatin. Examples of the compound which causes the substrate to swell include resorcinol and p-chlorophenol. Examples of a hardening agent for gelatin which can be used in the substratum include chromates (e.g., chrome alum), aldehydes (e.g., formaldehyde and glutaraldehyde), isocyanates, active halogen compounds (e.g., 2,4-dichloro-6-hydroxy-s-triazine), an epichlorohydrin resin and active vinylsulfone compounds. Further, the substrate may contain SiO₂, TiO₂, grains of an inorganic material or grains of a copolymer of polymethyl methacrylate (0.01 to 10 µm) as a matting agent.

Furthermore, it is preferable to record photographic information using a support provided with a magnetic recording layer and described in Japanese Patent Application Laid-Open (JP-A) Nos. 4-124,645, 5-40,321, 6-35,092 and 6-317,875.

A magnetic recording layer is formed by applying an aqueous or organic solvent-based coating solution containing a binder and magnetic grains dispersed therein to a support.

Examples of usable magnetic grains include ferromagnetic iron oxide such as γ-Fe₂O₃, Co-covered γ-Fe₂O₃, Co-covered magnetite, Co-containing magnetite, ferromagnetic chromium dioxide, ferromagnetic metals, ferromagnetic alloys, hexagonal Ba ferrite, Sr ferrite, Pb ferrite and Ca ferrite. A Co-covered ferromagnetic iron oxide such as Co-covered γ-Fe₂O₃ is preferred. The shape of the magnetic grains can be selected from the group consisting of needles, grains, spheres, cubes and plates. The specific surface area in SBET is preferably 20 m²/g or more, more preferably 30 m²/g or more. The saturation magnetization (as) of the ferromagnetic grains is preferably in the range of 3.0 x 10⁴ to 3.0 x 10⁵ A/m, more preferably 4.0 x 10⁴ to 2.5 x 10⁵ A/m. The ferromagnetic grains can be surface-treated with silicon dioxide and/or aluminum oxide or with an organic substance. Further, the ferromagnetic grains may be surface-treated with a silane coupling agent or a titanium coupling agent as described in Japanese Patent Application Laid-Open (JP-A) No. 6-161,032. Magnetic grains covered with an inorganic or organic substance described in Japanese Patent Application Laid-Open (JP-A) Nos. 4,259,911 and 5-81,652 may also be used in the present invention.

As described in Japanese Patent Application Laid-Open (JP-A) No. 4,219,569, the binders usable with the magnetic grains are thermoplastic resin, thermosetting resin, radiation-curing resin, reactive resin, acid- or alkali-degradable polymer or biodegradable polymer, naturally occurring polymer (e.g., cellulose derivatives and derivatives of saccharides) and mixtures thereof. These resins have a Tg in the range of 40 to 300°C and a weight average molecular weight in the range of 2,000 to 1,000,000. Preferred examples of the binder include vinyl-based copolymers, cellulose derivatives such as cellulose diacetate, cellulose triacetate, cellulose acetate propionate, cellulose acetate butyrate and cellulose tripropionate, acrylic resins, polyvinyl acetal resins and gelatin. Cellulose di(tri)acetate is particularly preferred. The binder can be cured by using a crosslinking agent such as an epoxy-, aziridine- or isocyanate-type crosslinking agent. Examples of the isocyanate type crosslinking agent include isocyanates such as tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate and xylylene diisocyanate, a reaction product of any of these isocyanates with a polyalcohol (e.g., a tolylene diisocyanate/trimethylolpropane adduct in a molar ratio of 3/1), and a polyisocyanate prepared by a condensation reaction of these isocyanates, all of which are described in, for example, Japanese Patent Laid-Open (JP-A) No. 6-59,357.

As described in Japanese Patent Laid-Open (JP-A) No. 6-35,092, the above-mentioned magnetic grains are dispersed in a binder preferably by means of a kneader, a pin mill or a ring mill. A combination of these dispersing devices is also preferred. A dispersing agent such as the dispersing agent described in Japanese Patent Laid-Open (JP-A) No. 5-88,283 and other known dispersing agents can be used to disperse the magnetic grains in the binder. The thickness of the magnetic recording layer is in the range of 0.1 to 10 µm, preferably 0.2 to 5 µm, and more preferably 0.3 to 3 µm. The ratio of the weight of the magnetic grains to the weight of the binder is preferably in the range of 0.5:100 to 60:100, more preferably 1:100 to 30:100. The coated weight of the magnetic grains is in the range of 0.005 to 3 g/m², preferably 0.01 to 2 g/m², and more preferably 0.02 to 0.5 g/m². The yellow transmission density of the magnetic recording layer is preferably in the range of 0.01 to 0.50, more preferably 0.03 to 0.20, and most preferably 0.04 to 0.15. The magnetic recording layer can be formed on the entire surface or on a strip on the back of a photographic support by coating or printing the coating solution for forming the magnetic recording layer. Usable methods for forming the magnetic recording layer include an air doctor method, a blade method, an air knife method, squeezing, impregnation, reverse roll coating, transfer roll coating, gravure coating, roll coating, casting, spraying, dipping, bar coating and extrusion. The coating solution described in, for example, Japanese Patent Application Laid-Open (JP-A) No. 5-341,436 is preferably used.

The magnetic recording layer can also function in enhancing sliding, controlling rolling, preventing electrostatic charge, preventing sticking and polishing the head. Another functional layer having one or each of these functions can also be formed. The abrasive grains which impart the function of polishing the head to the magnetic recording layer or other functional layer preferably contain at least one type of grain having a Mohs hardness of 5 or more and are non-spherical shaped inorganic grains. Examples of the non-spherical Inorganic grains include oxides such as alumina, chromium oxide, silica and titanium dioxide, carbides such as silicon carbide and titanium carbide, and diamond. The surface of the abrasive grains may be treated with a silane coupling agent or a titanium coupling agent. These grains may be added to the magnetic recording layer. Alternatively, the magnetic recording layer may be coated with a coating solution (e.g., a protective layer and a slip layer) containing these grains. As for the binder in the coating, the same binders as those mentioned above can be used, and the binder in the coating is preferably the same as the binder for the magnetic recording layer. The photosensitive materials having a magnetic recording layer are described in U.S. Patent Nos. 5,336,589, 5,250,404, 5,229,259 and 5,215,874 and in EP 466,130.

A polyester support preferably used in the photosensitive material having the magnetic recording layer described above is described below. Details of the polyester support together with a photosensitive material, a processing method, a cartridge and application examples thereof are described in JIII Journal of Technical Disclosure No. 94-6,023 (published on March 15, 1994 by The Japan Institution of Invention and Innovation).

The polyester is made from a diol and an aromatic dicarboxylic acid. Examples of the aromatic dicarboxylic acid include 2,6-, 1,5-, 1,4- and 2,7-naphthalenedicarboxylic acid, terephthalic acid, isophthalic acid and phthalic acid. Examples of the diol include diethylene glycol, triethylene glycol, cyclohexanedimethanol, bisphenol A and bisphenol. Examples of polymers formed from these monomers include homopolymers such as polyethylene terephthalate, polyethylene naphthalate and polycyclohexanedimethanol terephthalate. A polyester in which 2,6-naphthalenedicarboxylic acid accounts for 50 to 100 mol% of the carboxylic acid monomer composition is preferred, and polyethylene 2,6-naphthalate is particularly preferred. The average molecular weight of the polyester is in the range of 5,000 to 200,000. The Tg value of the polyester is 50ºC or more, preferably 90ºC or more.

Next, in order to suppress its curling, the polyester support is subjected to a heat treatment at a temperature which is preferably above 40°C but below the Tg value, more preferably above (Tg-20)°C but below the Tg value. The heat treatment may be carried out in a continuous manner at a temperature in the above-mentioned range, or it may be carried out in a discontinuous manner such that a cooling step is carried out between heat treatment steps. The duration of the heat treatment is preferably in the range of 0.1 to 1500 hours, more preferably 0.5 to 200 hours. The heat treatment may be carried out while the support is kept in the form of a roll, or the heat treatment may be carried out while the support is in the form of a web, which is being transported. Electrically conductive inorganic grains such as SnO₂ or Sb₂O₅ may be provided on the surface of the support to give it a surface roughness so that the surface state is improved. Further, it is preferable that the support is constructed in such a manner that the ends of the roll are slightly raised from other parts so that the transfer of the cut end mark of the roll core is prevented. Although the heat treatment can be carried out after film formation, after surface treatment, after application of a back coat (e.g., antistatic agent, lubricant) and after application of a primer, the heat treatment is preferably carried out after application of an antistatic agent.

An ultraviolet absorber may be mixed into the polyester. Further, to prevent light transmission, a dye or pigment commercially available for use in polyester under the names "Diaresin" (from Mitsubishi Chemical Industries, Co., Ltd.) or "Kayaset" (from Nihon Kayaku Co., Ltd.) may be mixed into the polyester.

A film cartridge (film container) in which the photosensitive material of the present invention can be enclosed will be explained below. The main material of the film cartridge may be a metal or a plastic.

Preferred examples of the plastic material include polystyrene, polyethylene, polypropylene and polyphenyl ether. The film cartridge may contain an antistatic agent, examples thereof include carbon black, metal oxide grains, surfactants such as nonionic, anionic, cationic or betaine-based surfactants, and polymers. Examples of the film cartridges which have been made antistatic are described in Japanese Patent Application Laid-Open (JP-A) Nos. 1-312,537 and 1-312,538. The resistivity of the film cartridge is preferably 10¹² Ω·cm or less at 25°C and 25% RH. Usually, carbon black or a pigment is incorporated into the plastic film cartridge to achieve light protection. The size of the film cartridge may be 135 size which is currently used (the diameter of the sleeve of 135 size is 25 mm). For use in a small-sized camera, a film cartridge with a sleeve diameter of 22 mm or less may be used. The cartridge volume of the film cartridge is 30 cm³ or less, preferably 25 cm³ or less. The weight of the plastics for a film cartridge is preferably in the range of 5 to 15 g.

For the photosensitive material of the present invention, a film cartridge which discharges the film by the rotation of a spool can be used. A film cartridge in which the film end is discharged outward from the discharge port of the film cartridge by rotating the spool axis in the discharge direction of the film can also be used. These film cartridges are described in U.S. Patent Nos. 4,834,306 and 5,226,613.

As for the method for forming an image on a sheet of color paper or on a photosensitive material for heat development, the methods described in Japanese Patent Application Laid-Open (JP-A) Nos. 5,241,251, 5-19,364 and 5-19,363 can be used.

Examples of a usable method for making a copy on a sheet of a color paper or on a light-sensitive material for use in heat development using the above-mentioned silver halide color photographic materials are described in, for example, JP-A Nos. 5-241,251, 5-19,364 and 5-19,363.

EXAMPLES

To better explain the present invention, the following examples are presented by way of illustration and not by way of limitation.

EXAMPLE 1 (1) Preparation of an emulsion (Tabular grain silver iodobromide emulsion 1-A (a comparison emulsion))

The pH of 1000 ml of an aqueous solution containing 0.5 g of oxidation-treated gelatin and 0.37 g of KBr was adjusted to 2 by adding H2SO4, and the reaction mixture was stirred at 40°C. To the reaction mixture were simultaneously added 20 ml of a 0.3 M AgNO3 aqueous solution (A) and 20 ml of a 0.3 M KBr aqueous solution (B) in 40 seconds by double jet. After the pH of the reaction mixture was adjusted to 5.0 by adding NaOH and the pAg was adjusted to 9.9 by adding a KBr solution, the temperature of the reaction mixture was then raised to 70°C in 35 minutes. At this temperature, after adding 35 g of oxidation-treated gelatin, 921 ml of a 1.2 M AgNO3 aqueous solution (C) and 800 ml of a 1.4 M KBr aqueous solution (D) were added in 33 minutes while accelerating the flow rate (the final flow rate is 7.2 times the initial flow rate) while maintaining the pAg at 8.58.

The reaction mixture was cooled to 55°C, and 80 ml of a 0.4 M AgNO3 aqueous solution (E) and 223 ml of a 0.12 M KL aqueous solution (F) were added to the reaction mixture in 3 minutes at a constant flow rate. After the pAg was adjusted to 8.8 by adding an aqueous KBr solution, 115 ml of a 1.8 M AgNO3 aqueous solution (G) and 131 ml of a 1.8 M KBr aqueous solution (H) were then added to the reaction mixture.

The temperature of the reaction mixture was then lowered to 35°C and thereafter the reaction mixture was evaporated in a conventional manner using a flocculant ("Demole", manufactured by Kao Corporation). After a water wash, 75 g of gelatin and 10 ml of phenoxyethanol were added to the flocculated product, which was adjusted to pH 5.5 and pAg 8.2.

In this way, an emulsion was obtained in which the projected area of tabular grains exceeded 99% of the total projected area of all the grains, and the tabular grains consisted of hexagonal tabular grains having an aspect ratio of 23.9, an average spherical equivalent diameter of 0.76 µm, an average grain thickness of 0.08 µm and an average circular equivalent diameter of 1.91 µm.

The above values of mean grain thickness and mean spherical equivalent diameter were obtained from photographs by a replica method using a transmission electron microscope.

The following tabular grain silver iodobromide emulsions 1-B to 1-D were prepared in the same manner as in the case of tabular grain silver iodobromide emulsion 1-A, but with the exceptions described below. The average grain aspect ratio and average spherical equivalent diameter of the resulting tabular grain silver iodobromide emulsions 1-B to 1-D were approximately the same as those of iodobromide grain emulsion 1-A.

(Tabular Grain Silver Iodobromide Emulsion 1-B (Comparative Silver Halide Emulsion))

The procedure for preparing the tabular grain silver iodobromide emulsion 1-A was repeated except that the solution (H) contained tripotassium iridium hexachloride in an amount of 1 x 10-7 mol in terms of iridium.

(Tabular grain silver iodobromide emulsion 1-C (a light-sensitive silver halide emulsion to be used in the present invention))

The procedure for preparing the tabular grain silver iodobromide emulsion 1-A was repeated except that the solution (H) contained potassium ferrocyanide in an amount of 6 x 10-5 mol based on iron.

(Silver iodobromide tabular grain emulsion 1-D (a comparison emulsion))

The procedure for preparing the tabular grain silver iodobromide emulsion 1-A was repeated except that the solution (H) contained tripotassium rhodium hexabromide in an amount of 2 x 10-8 mol in terms of rhodium.

(2) Chemical sensitization

At a temperature of 60°C, pH of 6.2 and pAg of 8.4, spectral sensitization and chemical sensitization of the tabular grain silver iodobromide emulsions 1-A to 1-D were carried out by adding the following spectral sensitizing dyes (sensitizing dyes I to III for green-sensitive emulsion), the following compound I and a selenium sensitizer together with potassium thiocyanate, chloroauric acid and sodium thiosulfate. The following chemical sensitization terminator was used to terminate the chemical sensitization.

The amount of the chemical sensitizer (selenium sensitizer) was adjusted so that the sensitivity of each of the tabular silver iodobromide emulsions was maximum at an exposure of 11100 seconds. Besides, in the case of the tabular silver iodobromide emulsions 1-C and 1-D, zinc nitrate was added to the tabular silver iodobromide emulsion at the time when gelatin was dispersed in the emulsion after the water washing step. Sensitizing dye I for a green sensitive emulsion Sensitizing dye II for a green sensitive emulsion Sensitizing dye III for a green sensitive emulsion

I : II : III = 17 : 4 : 2 (molar ratio) for the mixture

(3) Preparation of a dispersion and a coated material and its evaluation

A dispersion of zinc hydroxide was prepared to be used as a base precursor.

31 g of zinc hydroxide powder having primary particles with a particle size of 0.2 µm, 1.6 g of carboxymethylcellulose and 0.4 g of sodium polyacrylate as a dispersant, 8.5 g of lime-treated ossein gelatin and 158.5 ml of water were mixed. Then, the resulting mixture was dispersed for 1 hour by means of a mill using glass beads. After dispersion, the glass beads were removed and 188 g of a zinc hydroxide dispersion was obtained.

A dispersion of a magenta coupler was prepared.

7.80 g of magenta coupler (a), 5.45 g of developing agent (b), 8.21 g of high boiling point organic solvent (d) and 24.0 ml of ethyl acetate were dissolved at 60°C to prepare a solution. The previously prepared solution was added to 150 g of aqueous solution containing 12.0 g of lime-treated gelatin and 0.6 g of sodium dodecylbenzenesulfonate and mixed therewith. Then, the resulting mixture was dispersed for 20 minutes by means of a dissolving stirrer at 10,000 rpm. After complete dispersion, distilled water was added to the resulting dispersion to make a total of 300 g and mixed therewith at 2,000 rpm for 10 minutes.

These dispersions were combined with the tabular silver iodobromide emulsion 1-A to prepare the composition shown in Table 1. Then, the composition was coated on a support to prepare a photosensitive single layer (sample 101) containing a developing agent. Similarly, the silver halide color photographic photosensitive material of the present invention (sample 103) and photosensitive materials (102 and 104) were prepared by replacing "1-A" with "1-B", "1-C" or "1-D" in Table 1. An antifoggant (c) was added when a coating liquid for a magenta color layer was prepared. Table 1

Next, a processing material P-1 having the composition shown in Tables 2 and 3 was prepared.

Table 2 shows the details of processing layers formed on a support (transparent support A) to prepare a processing material P-1. Table 3 shows the details of the support (transparent support A). Table 2 Table 3

Water-soluble polymer (j): κ-carrageenan

Water soluble polymer (k): Sumikagel L-5H (from Sumitomo Chemical Co., Ltd.)

Samples 101 to 104 were exposed to light for 1110000 seconds using the "Sensitometer MRRKVII" manufactured by EGG Corporation through an optical wedge and a green filter.

After exposure, heat development was carried out by the method comprising supplying 15 ml/m² of warm water at 40°C to the photosensitive layer (magenta color layer, intermediate layer and protective layer) of each of the samples, bonding the photosensitive layer of each of the samples and the processing layer (the first to fourth layers) of a processing material P-1, face to face, and then heating the materials to 78°C and keeping them at that temperature for 17 seconds using a heat drum. A wedge-shaped magenta image was obtained in the samples when the samples were removed from the processing material P-1 after the first processing by the method described above.

Then, Samples 101 to 104 were subjected to a second processing using a second processing material P-2 shown in Table 4. The "compound 2" shown in Table 4 is as previously described. The details of the "transparent support A" are shown in Table 3. Table 4

The second processing was carried out by the method comprising supplying 10 ml/m² of water to the processing layer (the first to fourth layers) of the second processing material P-2, joining, face to face, the processing layer and the photosensitive layer of each of the samples 101 to 104 subjected to the first processing, and then heating the materials to 60°C and keeping them at that temperature for 30 seconds.

After the second processing, the samples were subjected to transmission density measurement to obtain a so-called characteristic curve. The sensitivity was expressed by a relative value obtained by taking the reciprocal of the exposure amount corresponding to a density higher than the fog density by 0.15 and setting the reciprocal of Sample 101 as 100. The sensitivities of Samples 102 to 104 were expressed as a relative value based on the sensitivity of Sample 101. Then, in order to evaluate the density variation depending on the change in temperature in the photosensitive material at the time of heat development, the change in density AD at a heat development temperature of 83°C was examined at an exposure amount required to produce a density of 1 under the condition of 17 seconds at 78°C. The sensitivity Dmin, the density change ΔD with temperature and the unevenness by visual inspection of the image in the middle density region when heat development was carried out at 80ºC were evaluated and are shown in Table 5. In Table 5, X means "unacceptable", Δ means "acceptable" and ○ means "OK". Table 5

From the results of Table 5, it can be seen that the unevenness of the image corresponds to the density change depending on the change of the processing temperature in the heat development, and that the unevenness of the image is reduced by using a light-sensitive silver halide emulsion composed of tabular grains containing metal ions or metal complex ions which are a shallow electron trap, because higher sensitivity is obtained and because the temperature dependence of the density change in the heat development is reduced.

EXAMPLE 2

A method for preparing an ultrafine silver chloride emulsion 2-(a) for epitaxial bonding is described below. To a sufficiently stirred aqueous solution of gelatin having the composition shown in Table 6 and a pH of 4, liquid (I) and liquid (II) of Table 7 were simultaneously added over 3 minutes, and 5 minutes thereafter, liquid (III) and liquid (IV) of Table 7 were simultaneously added over 5 minutes.

Table 6 Composition of the aqueous solution of gelatin

H₂O 650 cm³

gelatin processed with lime 10 g

NaCl 0.05g

1N sulphuric acid 4 cm³

N,N'-Dimethylimidazoline-2-dione 0.001 g

Temperature 3.5ºC Table 7

The reaction mixture was flocculated, rinsed and desalted in a conventional manner (flocculating agent: "Demole" manufactured by Kao Corporation). Then, 22 g of lime-processed gelatin was added to the product, which was adjusted to pH 6.1 and pAg 7.1. After adjustment, phenoxyethanol was added. The ultrafine silver chloride emulsion 2-(a) for epitaxial junction thus obtained was composed of cubic grains having an average side length of 0.06 µm. The yield was 635 g.

(Preparation of silver iodobromide emulsion 2-A (a comparative emulsion) composed of tabular grains with epitaxial bonding)

The procedure for tabular silver iodobromide emulsion 1-A was repeated except that 10 minutes after the addition of sensitizing dyes for chemical sensitization, 35 g of ultrafine silver chloride emulsion 2-(a) for epitaxial bonding was added to the emulsion. Then, to the resulting tabular grain silver iodobromide emulsion, chloroauric acid, sodium thiosulfate and selenium sensitizer were added in appropriately adjusted amounts so that the sensitivity of the resulting tabular silver iodobromide emulsion was maximum at an exposure of 1/10000 second.

(Preparation of silver iodobromide emulsion 2-B (a reference light-sensitive silver halide emulsion) composed of tabular grains having an epitaxial junction)

The procedure for the tabular silver iodobromide emulsion 1-B was repeated except that 10 minutes after the addition of sensitizing dyes for chemical sensitization, 35 g of the ultrafine silver chloride emulsion 2-(a) for epitaxial compound were added to the emulsion. Then, to the resulting tabular grain silver iodobromide emulsion, chloroauric acid, sodium thiosulfate and selenium sensitizer were added in appropriately adjusted amounts so that the sensitivity of the resulting tabular grain silver iodobromide emulsion was maximum at an exposure of 1/10000 second.

(Preparation of silver iodobromide emulsion 2-C (a reference light-sensitive silver halide emulsion) composed of epitaxially bonded tabular grains)

The procedure for the tabular silver iodobromide emulsion 1-C was repeated except that 10 minutes after the addition of sensitizing dyes for chemical sensitization, 35 g of the ultrafine silver chloride emulsion 2-(b) for epitaxial bonding was added to the emulsion, the ultrafine silver chloride emulsion 2-(b) being identical to the ultrafine silver chloride emulsion 2-(a) for epitaxial bonding except that the ultrafine silver chloride emulsion 2-(b) for epitaxial bonding contained tripotassium iridium hexachloride in an amount of 4.5 x 10-7 mol in terms of iridium per mol of silver. Then, to the resulting tabular grain silver iodobromide emulsion were added chloroauric acid, sodium thiosulfate and selenium sensitizer in appropriately adjusted amounts so that the sensitivity of the resulting tabular grain silver iodobromide emulsion was maximum at an exposure of 1/10000 second.

(Preparation of a silver iodobromide emulsion 2-D (a reference light-sensitive silver halide emulsion) composed of tabular grains having an epitaxial junction)

The procedure for tabular silver iodobromide emulsion 1-A was repeated except that 10 minutes after the addition of sensitizing dyes for chemical sensitization, 35 g of ultrafine silver chloride emulsion 2-(b) for epitaxial bonding was added to the emulsion. Then, to the resulting tabular grain silver iodobromide emulsion, chloroauric acid, sodium thiosulfate and selenium sensitizer were added in appropriately adjusted amounts so that the Sensitivity of the resulting tabular silver iodobromide emulsion was maximum at an exposure of 1/10000 second.

(Preparation of silver iodobromide emulsion 2-E (a light-sensitive silver halide emulsion to be used in the present invention) composed of tabular grains having an epitaxial junction)

The procedure for the tabular silver iodobromide emulsion 1-A was repeated except that 10 minutes after the addition of sensitizing dyes for chemical sensitization, 35 g of the ultrafine silver chloride emulsion 2-(c) for epitaxial bonding was added to the emulsion, the ultrafine silver chloride emulsion 2-(c) being identical to the ultrafine silver chloride emulsion 2-(a) for epitaxial bonding except that the ultrafine silver chloride emulsion 2-(c) for epitaxial bonding contained potassium ferrocyanide in an amount of 1.5 x 10-3 mol in terms of iron per mol of silver. Then, to the resulting tabular grain silver iodobromide emulsion were added chloroauric acid, sodium thiosulfate and selenium sensitizer in appropriately adjusted amounts so that the sensitivity of the resulting tabular grain silver iodobromide emulsion was maximum at an exposure of 1/10000 second.

Emulsions 2-A to 2-E were composed of grains each having a configuration in which a hexagonal tabular grain had fine grains bonded to its edges by means of an epitaxial bond. The average aspect ratio and average spherical equivalent diameter of each of Emulsions 2-A to 2-E were approximately the same as those of Emulsion 1-A.

The procedure for preparing Sample 101 in Example 1 was repeated except that the emulsion used therein was replaced with Emulsions 2-A to 2-E in Example 1, and as a result, Samples 201 to 205 were prepared.

The samples were processed, exposed and subjected to heat development as in Example 1. The results are shown in Table 8. In Table 8, the criteria for image unevenness are the same as those in Table 5. Table 8

From the results in Table 8, it can be seen that the epitaxial tabular grains have the problem that the density change of the image increases depending on the heat generation temperature variation although the sensitivity increases, and that if metal ions or metal complex ions which are a flat electron trap are used, the stability against the heat generation temperature increases and the sensitivity further increases.

EXAMPLE 3 (Preparation of silver chlorobromide emulsion (100) with tabular grain 3-A (a comparative emulsion))

1200 ml of an aqueous gelatin solution having a pH of 4.3, containing 25 g of alkali-treated ossein gelatin dissolved in deionized water and having a methionine content of about 40 µmol/g, 1 g of sodium chloride and 4.5 ml of 1N nitric acid were placed in a reactor, and thereafter the temperature of the solution was raised to 40°C. To this solution, which was vigorously stirred, were then added 36 ml of an aqueous solution (A) containing 20 g of silver nitrate per 100 ml and 36 ml of an aqueous solution (B) containing 0.71 g of potassium bromide and 6.67 g of sodium chloride per 100 ml simultaneously over a period of 45 seconds. After the addition was complete, the reaction mixture was stirred for 3 minutes and 43.4 ml of an aqueous solution (C) containing 1.1 g of potassium bromide per 100 ml was added over a period of 30 seconds. After the addition was complete, the temperature of the reaction mixture was lowered to 30°C in 3 minutes and the mixture was kept at that temperature. Then, 108 ml of the aqueous solution (A) and 108 ml of an aqueous solution (D) containing 7.02 g of sodium chloride per 100 ml were added to the reaction mixture. simultaneously over a period of 2 minutes and 15 seconds. After the addition was complete, the reaction mixture was stirred for 1 minute and then mixed with 20 ml of a 10% aqueous sodium chloride solution and 7 ml of a 1N aqueous sodium hydroxide solution so that the reaction mixture had a pH of 6.5 and a silver potential of 80 mV versus a saturated calomel electrode. Thereafter, 2 ml of a hydrogen peroxide solution (35%) was added to the reaction mixture. The temperature of the reaction mixture was then raised to 75°C and the reaction mixture was allowed to mature at 75°C for 5 minutes.

Then, to the reaction mixture was added 1086 g of an ultrafine silver chlorobromide emulsion 3-(a) acting as an epitaxial compound, identical to the ultrafine silver chloride emulsion 2-(a) acting as an epitaxial compound, except that the ultrafine silver chlorobromide emulsion 3-(a) acting as an epitaxial compound had a silver bromide content of 5 mol%, and was added over a period of 45 minutes while maintaining the silver potential of the reaction mixture at a value of 140 mV. The temperature was then lowered to 35°C, and salting out was carried out in a usual manner.

Thus, a tabular grain silver chlorobromide emulsion 3-A was obtained which was composed of tabular grains of silver chlorobromide (100) having an average grain size of 0.92 µm in terms of average spherical equivalent diameter, an average grain thickness of 0.128 µm, an average aspect ratio of 15.9 and a silver bromide content of 5 mol%.

Chemical sensitization of the tabular grain silver chlorobromide emulsion 3-A was carried out as in the case of the tabular grain silver iodobromide emulsion 1-A except that KI in an amount of 10⁻³ mol per mol of silver and a degradation product of ribonucleic acid were added to the emulsion after the addition of the sensitizing dyes.

The following tabular grain silver chlorobromide emulsions 3-B to 3-E were prepared in the same manner as in the case of the tabular grain silver chlorobromide emulsion 3-A, but with the exceptions described below. The average grain aspect ratio and the average spherical equivalent diameter of each of the resulting tabular grain silver chlorobromide emulsions 3-B to 3-E were the same as that of the tabular grain silver chlorobromide emulsion 1-A.

(Silver chlorobromide emulsion (100) with tabular grain 3-B (a light-sensitive silver halide emulsion to be used in the present invention))

The procedure for preparing tabular grain silver chlorobromide emulsion 3-A was repeated except that an ultrafine silver chlorobromide emulsion 3-(b) which was identical to emulsion 3-(a) except that emulsion 3-(b) contained potassium ferrocyanide in an amount of 2 x 10-4 mol in terms of iron per mol of silver was added to the emulsion. The tabular grain silver chlorobromide emulsion 3-B thus obtained was subjected to the same chemical sensitization as that for emulsion 3-A.

(Tabular grain epitaxial silver chlorobromide emulsion (100) 3-C (a comparative emulsion))

The procedure for Emulsion 3-A was repeated except that 10 minutes after the addition of sensitizing dyes for chemical sensitization, Kl was not added, but 35 g of Emulsion 3-(c) which is identical to Emulsion 2-(a) except that Emulsion 3-(c) had a silver bromide content of 100 mol% was added to the emulsion. Then, the resulting emulsion was added with chloroauric acid, sodium thiosulfate and selenium sensitizer.

(3-D tabular grain epitaxial silver chlorobromide emulsion (100) (a light-sensitive silver halide emulsion to be used in the present invention))

The procedure for Emulsion 3-B was repeated, and Emulsion 3-D was prepared except that 10 minutes after the addition of sensitizing dyes for chemical sensitization, Kl was not added, but 35 g of an emulsion 3-(c) identical to Emulsion 2-(b) except that Emulsion 3-(c) had a silver bromide content of 100 mol% was added to the emulsion. Then, chloroauric acid, sodium thiosulfate and selenium sensitizer were added to the obtained emulsion.

(Tabular grain epitaxial silver chlorobromide emulsion (100) 3-E (a light-sensitive silver halide emulsion to be used in the present invention))

The procedure for Emulsion 3-A was repeated, and Emulsion 3-E was prepared except that 10 minutes after the addition of sensitizing dyes for chemical sensitization, Kl was not added, but 35 g of an emulsion 3-(d) identical to Emulsion 3-(c) except that Emulsion 3-(d) potassium ferrocyanide in an amount of 5 x 10-4 mol in terms of iron was added to the emulsion. Then, chloroauric acid, sodium thiosulfate and selenium sensitizer were added to the obtained emulsion.

Emulsions 3-C, 3-D and 3-E were composed of grains each having a configuration in which a rectangular tabular (100) grain had fine grains bonded to its corners by epitaxial bonding.

The procedure for preparing Sample 101 in Example 1 was repeated except that the emulsion used therein was replaced with Emulsions 3-A to 3-E in Sample 101 and that the amount of the antifoggant (c) was increased to 8 mg/m², and as a result, Samples 301 to 305 were prepared.

As in Example 1, the samples were processed, exposed and subjected to heat development. The results are shown in Table 9. In Table 9, the sensitivities are relative values by setting the sensitivity of Sample 301 as 100, and the criteria for image unevenness in Table 9 are the same as those in Table 5. Table 9

From the results of Table 9, it is clear that the density change of the image depending on the temperature variation of the heat development is significant even in the case of emulsions composed of tabular grains with a higher silver chloride content, since the emulsions with a high silver chloride content have a high activity. However, it was found that the incorporation of metal ions or metal complex ions as a flat electron trap into the emulsion effectively inhibits the density change of the image depending on the temperature variation of the heat development while maintaining the high sensitivity of emulsions with a high silver chloride content. This effect is also significant in emulsions composed of grains with an epitaxial junction.

A comparative emulsion 3-F with a high silver chloride content was also used, composed of tabular (111) grains containing metal ions or metal complex ions as a flat electron trap, to prepare a photosensitive material subjected to the same heat development. As a result, the photosensitive material had excellent photographic properties without the formation of image unevenness.

The high silver chloride emulsion 3-F composed of tabular (111) grains was prepared in the following manner. 1200 ml of an aqueous gelatin solution containing 2.1 g of alkali-treated ossein gelatin dissolved in deionized water and 2 g of sodium chloride was placed in a reactor, and the solution was kept at 35°C. To this solution, which was vigorously stirred, were then added 1100 ml of an aqueous solution (A) containing 165 g of silver nitrate and 1100 ml of an aqueous solution (B) containing 59.1 g of sodium chloride at an increase of 60 ml of each solution simultaneously over a period of 1 minute. An aqueous solution (C) containing 0.285 g of a compound (3) was also prepared. 1 minute after the complete addition of solutions (A) and (B), 40 ml of solution (C) was added to the reaction mixture, and 30 ml of a 10% aqueous sodium chloride solution was also added to the reaction mixture 1 minute after the complete addition of solution (C). After the complete addition, the temperature of the reaction mixture was raised to 60ºC in 25 minutes, and 16 minutes later, 260 ml of an aqueous gelatin solution containing 29 g of phthalated gelatin was added to the reaction mixture, and another 3 minutes later, 10 ml of the solution (C) was added to the reaction mixture. Next, 1 minute later, 768 ml of the aqueous solution (A) and 768 ml of the aqueous solution (B) were simultaneously added to the reaction mixture at an initial rate of 2.85 ml/minute and at an acceleration of 0.818 ml/min2. 10 minutes before the complete addition of the solutions (A) and (B), the addition of a solution (D), that is, 270 ml of an aqueous solution containing 3.9 g of sodium chloride and 0.1 g of potassium ferrocyanide, began, so that the addition of the solution (D) was completed in 10 minutes. Further, 2 minutes before the complete addition of solutions (A) and (B), the addition of 34 ml of a 10% aqueous potassium bromide solution was started so that the addition of this solution was completed in 3 seconds. 3 minutes after the complete addition of solutions (A) and (B), 27 ml of a 1% aqueous potassium thiocyanate solution and 45 ml of a liquid containing 100 g of gelatin and dispersed therein 570 mg of a sensitizing dye I for green-sensitive emulsions, 60 mg of a sensitizing dye II for green-sensitive emulsions and 120 mg of a sensitizing dye III for green-sensitive emulsions were added to the reaction mixture. 1 minute after the addition, the temperature of the reaction mixture was raised to 75°C and this temperature was maintained for 10 minutes. The temperature of the reaction mixture was then lowered to 40°C, and desalting of the reaction mixture was carried out in a conventional manner using a flocculant (I). Then, the reaction product was dispersed in 67 g of ossein gelatin treated with an alkali dissolved in deionized water, mixed with zinc nitrate and phenoxyethanol to obtain an emulsion which was adjusted to pH 6.3 and pAg 7.7.

The resulting emulsion was found to contain 3-F grains consisting of tabular (111) silver chlorobromide grains having an average grain size of 0.74 µm, expressed as sphere equivalent diameter, an average aspect ratio of 8.7, and a silver bromide content of 5 mol%.

Emulsion 3-F was chemically sensitized at 60ºC to give the emulsion maximum sensitivity by the sequential addition of a compound (4), 4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene, sodium sulfate, a selenium sensitizer, chloroauric acid and sodium benzenethiosulfonate. Chemical sensitization was terminated by the addition of compound (4).

EXAMPLE 4 (Tabular grain silver iodobromide emulsion 4-A (a comparison emulsion))

A mixture of 0.74 g of gelatin with an average molecular weight of 12,000, 0.3 g of KBr and 930 ml of distilled water was placed in a reactor, and then the temperature of the mixture was raised to 35°C. To this solution, which was vigorously stirred, were then added 30 ml of an aqueous solution (A) containing 1.2 g of AgNO₃ and 30 ml of an aqueous solution (B) containing 0.82 g of KBr over a period of 20 seconds. After the addition was complete, the reaction mixture was kept at 40°C for 1 minute, and then the temperature of the reaction mixture was to 75°C. Then, 27.0 g of oxidation-treated gelatin was added together with 200 ml of distilled water to the reaction mixture. Further, 100 ml of an aqueous solution (C) containing 22.5 g of AgNO3 and 80 ml of an aqueous solution (D) containing 15.43 g of KBr were added to the reaction mixture over a period of 11 minutes in such a manner that the flow rate of addition gradually increased. Next, 250 ml of an aqueous solution (E) containing 75.1 g of AgNO3 was added. and 210 ml of an aqueous solution (F) containing Kl in a molar ratio of Kl:KBr of 3:97 (KBr concentration: 26%) were added to the reaction mixture in such a manner that the flow rate of addition was gradually increased and that the silver potential of the reaction mixture was 0 mV versus a saturated calomel electrode. After the addition was complete, the reaction mixture was kept at 75°C for 1 minute, and thereafter the temperature of the reaction mixture was lowered to 55°C. Then, 120 ml of an aqueous solution (I) containing 8.1 g of AgNO₃ and 320 ml of an aqueous solution (J) containing 7.26 g of Kl were added to the reaction mixture over a period of 5 minutes. After the addition was complete, 5.5 g of KBr was added to the reaction mixture, and the temperature of the reaction mixture was kept at 55°C for 1 minute. Further, 180 ml of an aqueous solution (K) containing 44.3 g of AgNO3 and 160 ml of an aqueous solution (L) containing 34.0 g of KBr were added to the reaction mixture over a period of 8 minutes. Then, the temperature of the solution was lowered and desalting was carried out in a conventional manner.

In this way, a tabular silver iodobromide emulsion 4-A was obtained in which the projected area of tabular grains exceeded 99% of the total projected area of all the grains, and the tabular grains had an average spherical equivalent diameter of 0.66 µm, an average grain thickness of 0.095 µm, an aspect ratio of 14.9 and an average circular equivalent diameter of 1.4 µm.

(Tabular grain silver iodobromide emulsion 4-B (a light-sensitive silver halide emulsion for use in the present invention))

The procedure for preparing the tabular grain silver iodobromide emulsion 4-A was repeated except that the solution (K) contained potassium ferrocyanide in a amount of 8 x 10-5 mol in terms of iron. The average aspect ratio and the average equivalent sphere diameter of the resulting emulsion were the same as those and those of Emulsion 4-A, respectively.

(Tabular grain silver iodobromide emulsion 4-C (a comparison emulsion))

A mixture of 12.5 g of gelatin with an average molecular weight of 15,000, 4.35 g of KBr, 0.32 g of KI and 950 ml of distilled water was placed in a reactor, and then the temperature of the mixture was raised to 45°C. To this solution, which was vigorously stirred, were then added 50 ml of an aqueous solution (A) containing 8.3 g of AgNO3 and 50 ml of an aqueous solution (B) containing 2.67 g of KBr over a period of 45 seconds. After the addition was complete, the reaction mixture was kept at 45°C for 4 minutes, and then the temperature of the reaction mixture was raised to 63°C. Then 17.0 g of gelatin was added to the reaction mixture together with 130 ml of distilled water. Further, 150 ml of an aqueous solution (C) containing 51.2 g of AgNO3 and a 24.8% aqueous solution (D) were added to the reaction mixture over a period of 13 minutes in such a manner that the flow rate of addition gradually increased and the silver potential of the reaction mixture was 0 mV against a saturated calomel electrode. After the addition was completed, the reaction mixture was kept at 63°C for 2 minutes, and thereafter the temperature of the reaction mixture was lowered to 45°C. Next, 50 ml of an aqueous solution (E) containing 5.9 g of AgNO3 and 320 ml of an aqueous solution (F) containing 5.82 g of KI were added to the reaction mixture over a period of 5 minutes. Further, 350 ml of an aqueous solution (G) containing 104.3 g of AgNO3 and a 25% aqueous solution of KI (H) were added to the reaction mixture over a period of 45 minutes in such a manner that the silver potential of the reaction mixture was 10 mV versus a saturated calomel electrode. After the addition was complete, 1.4 g of KI and 4 mg of sodium ethylthiosulfonate were added to the reaction mixture, which was kept at 45°C for 5 minutes. The temperature of the reaction mixture was then lowered and desalting was carried out in a conventional manner.

In this way, a tabular silver iodobromide emulsion 4-C was obtained which was composed of hexagonal tabular grains having an average spherical equivalent diameter of 0.37 µm and an average aspect ratio of 5.8.

(4-D tabular grain silver iodobromide emulsion (a light-sensitive silver halide emulsion to be used in the present invention))

The procedure for preparing the tabular grain silver iodobromide emulsion 4-A was repeated except that the solution (H) contained potassium ferrocyanide in an amount of 8 x 10-5 mol in terms of iron. The average aspect ratio and the average sphere equivalent diameter of the obtained emulsion were approximately the same as those of the emulsion 4-C.

Chemical sensitization of these emulsions was carried out in the same manner as for the comparative emulsion 1-A. That is, to the resulting tabular grain silver iodobromide emulsion, chloroauric acid, sodium thiosulfate and a selenium sensitizer were added in appropriately adjusted amounts so that the sensitivity of the resulting tabular grain silver iodobromide emulsion was maximum at an exposure of 1110000 seconds. The amounts of the dyes for spectral sensitization and chemical sensitization terminators were proportionally adjusted depending on the surface area of the grains of the emulsions.

The sensitization procedures for both the comparative tabular grain silver iodobromide emulsions 1-A, 4-A and 4-C and the tabular grain silver iodobromide emulsions according to the present invention 1-C, 4-B and 4-D were repeated except that the sensitizing dyes used therein were changed to sensitizing dyes (a mixture of sensitizing dyes V to VII for red-sensitive emulsions) for red-sensitive emulsions, and thus emulsions 1-A(r), 4-A(r), 4-C(r), 1-C(r), 4-B(r) and 4-D(r) were prepared. The sensitization procedures for both the tabular grain silver iodobromide emulsions for comparison 1-A, 4-A and 4-C and the tabular grain silver iodobromide emulsions according to the present invention 1-C, 4-B and 4-D were repeated except that the sensitizing dyes used therein were changed to a sensitizing dye (a sensitizing dye IV for blue-sensitive emulsions) for blue-sensitive emulsions, and thus 1-A(b), 4-A(b), 4-C(b), 1-C(b), 4-B(b) and 4-D(b) were prepared.

A multilayer photosensitive material (sample 401) shown in Tables 10 to 12 was prepared by using emulsions 1-A, 4-A and 4-C for a high sensitivity layer, a medium sensitivity layer and a low sensitivity layer in a green sensitive magenta coloring layer, and by using emulsions 1-A(r), 4-A(r) and 4-C(r) for a high sensitivity layer, a medium sensitivity layer and a low sensitivity layer in a red sensitive cyan coloring layer, and by using emulsions 1-A(b), 4-A(b) and 4-C(b) for a high sensitivity layer, a medium sensitivity layer and a low sensitivity layer in a blue sensitive yellow coloring layer.

Although Tables 10 through 12 are presented as three separate tables, they were originally one table containing these tables in that order. Table 10-1 Table 10-2 Table 11 Table 12-1 Table 12-2 Sensitizing dye IV for the blue sensitive emulsion Sensitizing dye V for the red sensitive emulsion Sensitizing dye VI for the red sensitive emulsion Sensitizing dye VII for the red sensitive emulsion

Mixture in molar ratio V : VI : VIII = 40 : 2 : 58

A silver halide multicolor color photographic light-sensitive material (Sample 402) of the present invention was prepared by repeating the procedure for Sample 401 except that the emulsions used therein were changed as shown below in Sample 401. That is, in the formulation of Sample 401, emulsions 1-A, 4-A and 4-C were replaced by emulsions 1-C, 4-B and 4-D, and emulsions 1-C, 4-B and 4-D were used for a high sensitivity layer, a medium sensitivity layer and a low sensitivity layer in a green sensitive magenta coloring layer, emulsions 1-C(r), 4-B(r) and 4-D(r) were used for a high sensitivity layer, a medium sensitivity layer and a low sensitivity layer in a red sensitive cyan coloring layer, and emulsions 1-C(b), 4-B(b) and 4-D(b) were used for a high sensitivity layer, a medium sensitivity layer and a low sensitivity layer in a blue sensitive cyan coloring layer. sensitive, yellow-colouring layer.

Meanwhile, according to the method for preparing dispersions of couplers as shown in Example 1, a cyan coupler dispersion and a yellow coupler dispersion were prepared. In addition, in order to prepare a color layer capable of losing color in a heat development process, a coloring dispersion was also prepared using a combination of the yellow, magenta and cyan leuco dyes with a zinc complex.

The photographic characteristics of Sample 402 were examined in the same manner as in Example 1 except that the filter was removed at the time of exposure.

Sample 402 was exposed for 1/10000 second by means of "Sensitometer MARKVII" manufactured by EGG Corporation through an optical wedge. After exposure, heat development was carried out by the method comprising supplying 20 ml/m² of warm water of 40ºC to the photosensitive layer of Sample 402, assembling the photosensitive layer and the processing layer of the first processing material P-3 face to face, and then heating the materials to 83ºC and keeping them at that temperature for 30 seconds using a heat drum. Then, the sample was 402 was removed from the processing material P-3, and the sample 402 was subjected to a second processing using a second processing material P-2. The second processing was carried out by the method comprising supplying 15 ml/m² of water to the processing layer of the second processing material P-2, assembling the processing layer and the photosensitive layer of sample 402 which had been subjected to the first processing face to face, and then heating the materials to 60°C while maintaining them at that temperature for 30 seconds using a heat drum. The image of sample 402 after the above-described processing was subjected to transmission density measurement of yellow, magenta and cyan wedge images by using blue, green and red filters to obtain a so-called characteristic curve. Incidentally, the processing material P-3 was the same as the processing material P-1 in Example 1 except that the amount of guanidine picolinate was changed to 4500 mg/m2.

The sensitivity was expressed by a relative value obtained by taking the inverse value of the exposure amount corresponding to a density higher than the fog density by 0.15 and setting the reciprocal value of Sample 401 as 100, as in Example 1. The sensitivities of Sample 402 were expressed in relative values based on the sensitivities of Sample 401. The results are shown in Table 13. Table 13

As is clear from Table 13, the effect of the present invention, characterized by high sensitivity and very low unevenness of image, is also observed in a multilayer silver halide multicolor color photographic material (Sample 402) as in Example 1.

EXAMPLE 5

A multilayer photosensitive material (sample 501) was prepared by repeating the procedure for sample 401 except that a medium-sensitivity layer and a low-sensitivity layer as used therein were removed from the blue-sensitive yellow coloring layer, the green-sensitive magenta coloring layer and the red-sensitive cyan coloring layer; emulsion 3-A was used for the high-sensitivity layer of the green-sensitive magenta coloring layer; emulsion 3-A(r), identical to emulsion 3-A except that a sensitizing dye for a red-sensitive layer was used in emulsion 3-A(r), was used for the high-sensitivity layer of the red-sensitive cyan coloring layer; and Emulsion 3-A(b), identical to Emulsion 3-A except that a sensitizing dye for a blue-sensitive emulsion was used in Emulsion 3-A(b), was used for the high-sensitivity layer of the blue-sensitive yellow-coloring layer.

Next, a silver halide color photographic light-sensitive material (Sample 502) of the present invention was prepared by repeating the procedure of Example 3 except that use was made of Emulsion 3-D(r), identical to Emulsion 3-D except that a sensitizing dye for a red-sensitive emulsion was used in Emulsion 3-D(r), Emulsion 3-D(b), identical to Emulsion 3-D except that a sensitizing dye for a blue-sensitive emulsion was used in Emulsion 3-D(b), and Emulsion 3-D.

These samples were processed as in Example 4. As a result, the silver halide color photographic light-sensitive material (Sample 502) exhibited the effect of the present invention characterized by high sensitivity and very little unevenness of image. On the other hand, the light-sensitive material (Sample 501) did not exhibit the above-mentioned effect of the present invention.

EXAMPLE 6

A sample was prepared by repeating the procedure for preparing the multilayer sample 402 in Example 4, except that the support (transparent PET support) used therein was replaced with a support prepared in the following manner and that the prepared sample was placed in a cartridge. When the sample was examined in the same manner as in Sample 4, the sample showed excellent results as in the case of Example 402, thereby confirming the effect of the present invention characterized by high sensitivity and very low image unevenness in a photosensitive material system containing a developing agent using a metal ion and/or metal complex ions which are flat electron traps.

The support used in Example 6 was prepared by the method described below.

A PEN film having a thickness of 90 µm was obtained by the process comprising drying 100 parts by weight of a polyethylene-2,6-naphthalate polymer and 2 parts by weight of Tinuvin P.326 (from Ciba-Geigy Co., Ltd.) as an ultraviolet ray absorber, melting these components at 300°C and extruding through a T-shaped die, stretching the extrudate to 3.3 times the original length in the machine direction at 140°C, stretching the extrudate to 3.3 times the original length in the transverse direction at 130°C, and thermally fixing the stretched film at 250°C for 6 seconds. Before preparation, an appropriate amount of a blue dye, a magenta dye and a yellow dye (I-1, I-4, I-6, I-24, I-26, I-27 and II-5 described in JIII Journal of Technical Disclosure No. 94-6023) were added to the PEN film. The PEN film was wound on a stainless steel core with a diameter of 20 cm and subjected to thermal hysteresis at 110°C for 48 hours to produce a low-curl support.

Both sides of the substrate were subjected to a sequence of processes including a corona discharge process, a UV irradiation process and a glow discharge process.

Then, a substratum was formed on both sides by applying a substratum forming solution containing the following materials: gelatin: 0.1 g/m², sodium (sulfo-di-2-ethylhexyl succinate: 0.01 g/m², salicylic acid: 0.04 g/m², p-chlorophenol: 0.2 g/m², (CH₂=CHSO₂CH₂CH₂NHCO)₂CH₂: 0.012 g/m² and a polyamide/epichlorohydrin polycondensation product: 0.02 g/m² (using a bar coater 10 cm³/m²).

After application, the substrate was dried at 115ºC for 6 minutes (all transport equipment, including rollers in the drying zone, were kept at 115ºC).

One side of the support coated with the substrate described above was coated with an antistatic layer, a transparent magnetic recording layer and a slipping layer having the following compositions, sequentially as back layers.

Application of an antistatic layer

An antistatic layer was formed by applying a solution containing the following materials: a dispersion of fine grains (with an average grain diameter of secondary grains of 0.08 µm) made of a tin oxide/antimony oxide complex oxide with an average grain diameter of 0.005 µm and a specific resistance of 5 Ω·cm: 0.2 g/m2, gelatin: 0.05 g/m2, (CH₂=CHSO₂CH₂CH₂NHCO)₂OH₂: 0.012 g/m2, a polyoxyethylene-p-nonylphenol (polymerization degree: 10): 0.005 g/m2 and resorcinol.

Application of a transparent, magnetic recording layer

A magnetic recording layer having a thickness of 1.2 µm was formed by coating the support with cobalt/γ-iron oxide grains mixed with 3-polyoxyethylenepropyloxytrimethoxysilane (polymerization degree: 15) (15 wt%) having a specific surface area of 43 m²/g, a major axis of 0.14 µm, a minor axis of 0.03 µm, a saturation magnetization of 89 emE/g, Fe⁺²/Fe⁺³ = 6/94 and surface-treated with alumina/silica in an amount corresponding to 2 wt%. of iron oxide: 0.06 g/m² using diacetyl cellulose: 1.2 g/m² (the dispersion of iron oxide was carried out by means of an open kneader and a sand mill), (C₂H₅C(CH₂CONH-C₆H₃(CH₃)NCC)₃: 0.3 g/m² as a hardener together with acetone, methyl ethyl ketone and dibutyl phthalate as a solvent using a bar coater. The following materials were added to the magnetic recording layer. A lubricant, ie, C₆H₁₃CH(OH)C₁₀H₂₀COOC₄₀H₈ₓ: 50 mg/m², a matting agent, ie, silica grains (1.0 µm): 50 mg/m², and an abrasive, ie, alumina grains (0.2 µm and 1.0 µm) coated with 3-polyoxyethylenepropyloxytrimethoxysilane (polymerization degree: 15) (15 wt%): 10 mg/m². After its application, the magnetic recording layer was dried at 115°C for 6 minutes (all transport means including rollers in the drying zone were kept at 115°C). The magnetic recording layer showed a color density DB increment under X-light (blue filter) of about 0.1, a saturation magnetization moment of 4.2 emE/g, a coercive force of 7.3 x 10⁴ A/m and a polygonal rate of 65%.

Application of a sliding layer

The support was coated with hydroxyethyl cellulose (25 mg/m2) together with a mixture of C6H13CH(OH)C10H20COOC40H81 (6 mg/m2) and silicone oil BYK-310 (available from Bic Chemie Japan Co., Ltd.: 1.5 mg/m2). The coating composition was prepared in the following manner: melting the above mixture in a mixture of xylene/propylene glycol monomethyl ether (1/1) at 105°C, emulsifying the product in propylene glycol monomethyl ether (in an amount 10 times the mixture) at room temperature, dispersing the resulting emulsion in acetone to prepare a dispersion (having an average grain diameter of 0.01 µm), and adding the dispersion to the hydroxyethyl cellulose. After its application, the slip layer was dried at 115°C for 6 minutes (all transport equipment, including rollers in the drying zone, were kept at 115°C). The sliding layer showed excellent properties, characterized by a coefficient of kinetic friction of 0.10 (using a hard, stainless steel ball with a diameter of 5 mm and a load of 100 g at a speed of 5 cm/minute), a coefficient of static friction of 0.08 (clamping method) and a coefficient of kinetic friction against a Emulsion coated surface of 0.15, which gives excellent characteristics.

EXAMPLE 7 (I) Preparation of an emulsion (Tabular grain silver iodobromide emulsion 1-E (a comparison emulsion))

The pH of 1000 ml of an aqueous solution containing 0.5 g of oxidation-treated gelatin and 0.37 g of KBr was adjusted to 2 by adding H2SO4, and the reaction mixture was stirred at 40°C. To the reaction mixture were simultaneously added 20 ml of a 0.3 M AgNO3 aqueous solution (A) and 20 ml of a 0.3 M KBr aqueous solution (B) in 40 seconds by double jet. After the pH of the reaction mixture was adjusted to 5.0 by adding NaOH and the pAg to 9.9 by adding a KBr solution, the temperature of the reaction mixture was then raised to 75°C in 35 minutes. After adding 35 g of oxidation-treated gelatin, 512 ml of 1.2 M AgNO3 aqueous solution (C) and 440 ml of 1.4 M KBr aqueous solution (D) were added at this temperature in 33 min while accelerating the flow rate (the final flow rate was 5.2 times the initial flow rate) while maintaining the pAg at 8.58.

The reaction mixture was cooled to 55°C, and 104 ml of a 0.4 M AgNO3 aqueous solution (E) and 279 ml of a 0.12 M KL aqueous solution (F) were added to the reaction mixture in 5 minutes at a constant flow rate. After the pAg was adjusted to 8.8 by the addition of a KBr aqueous solution, 110 ml of a 1.8 M AgNO3 aqueous solution (G) and 125 ml of a 1.8 M KBr aqueous solution (H) were then added to the reaction mixture.

The temperature of the reaction mixture was then lowered to 35°C, and thereafter the reaction mixture was flocculated in a conventional manner using a flocculant ("Demole", manufactured by Kao Corporation). After a In the water wash step, 75 g of gelatin and 10 ml of phenoxyethanol were added to the solubilizer, which was adjusted to pH 5.5 and pAg 8.2.

In this way, an emulsion was obtained in which the projected area of tabular grains exceeded 99% of the total projected area of all the grains, and the tabular grains consisted of hexagonal tabular grains having an aspect ratio of 29, an average spherical equivalent diameter of 0.65 µm, an average grain thickness of 0.06 µm and an average circular equivalent diameter of 1.75 µm.

The above values of mean grain thickness and mean circular equivalent diameter were obtained from photographs by a replica method using a transmission electron microscope.

The following tabular grain silver iodobromide emulsions 1-F to 1-H were prepared in the same manner as in the case of the tabular grain silver iodobromide emulsion 1-E, but with the exceptions described below. The average grain aspect ratio and the average spherical equivalent diameter of the resulting tabular grain silver iodobromide emulsions 1-F to 1-H were approximately the same as those of the iodobromide grain emulsion 1-E.

(Silver iodobromide tabular grain emulsion 1-F (a comparison emulsion))

The procedure for preparing the tabular grain silver iodobromide emulsion 1-E was repeated except that solution (D) contained tripotassium iridium hexachloride in an amount of 2 x 10-8 mol in terms of iridium.

(Silver iodobromide tabular grain emulsion 1-G (an emulsion to be used in the present invention))

The procedure for preparing tabular grain silver iodobromide emulsion 1-E was repeated except that solution (H) contained potassium ferrocyanide in an amount of 8 x 10-5 mol based on iron.

(Tabular grain silver iodobromide emulsion 1-H (a reference light-sensitive silver halide emulsion))

The procedure for preparing the tabular grain silver iodobromide emulsion 1-E was repeated except that the solution (D) contained tripotassium iridium hexachloride in an amount of 2 x 10-8 mol in terms of iridium and that the solution (H) contained potassium ferrocyanide in an amount of 8 x 10-5 mol in terms of iron.

(2) Chemical sensitization

The chemical sensitization procedure of Example 1 was repeated except that the molar ratio of spectral sensitization dyes (sensitizing dyes I to III for green sensitive emulsions) used therein was changed to 28:7:1. Besides, in the case of tabular grain silver iodobromide emulsions 1-G and 1-H, zinc nitrate was added to the emulsions in the dispersion step of gelatin after the water wash.

Photosensitive materials (samples 601 to 604) were prepared by replacing "1-A" in Table 1 with "1-E", "1-F", "1-G" and "1-H". An antifoggant (c) was added when a coating liquid for a magenta coloring layer was prepared.

Photosensitive materials (Samples 601A to 604A) were prepared by repeating the procedure for preparing Samples 601 to 604 except that the developing agent was not added to the emulsions (Samples 601A to 604A did not contain any developing agent).

Samples 601 to 604 were exposed to light of 1000 lux for 1/100 second via an optical wedge and a green filter.

After exposure, heat development was carried out by the method comprising supplying 15 ml/m² of warm water of 40ºC to the photosensitive layer (magenta coloring layer, intermediate layer and protective layer) of each of the samples, assembling the photosensitive layer of each of the samples and the processing layer (the first to fourth layers) of a processing material P-1, face to face, and then heating the materials to 80°C to keep them at that temperature for 17 seconds using a heat drum. A wedge-shaped magenta image was obtained in the samples when the samples were removed from the processing material P-1 after the first processing of the method described above.

Samples 601 to 604 were then subjected to a second processing using a second processing material P-2 as in Example 1.

After the second processing, the samples were subjected to transmission density measurement to obtain a so-called characteristic curve. The sensitivity was expressed by a relative value obtained by taking the reciprocal of the exposure amount corresponding to a density higher than the fog density by 0.15 and setting the reciprocal of Sample 601 as 100. The sensitivities of Samples 602 to 604 were expressed as a relative value based on the sensitivity of Sample 601. Besides, the samples were stored under accelerated storage conditions (5 days at 60°C and 40% RH) and were then exposed and processed as described above. The sensitivity of Dmin immediately after coating and the increase of ΔDmin in Dmin after the accelerated storage test are shown in Table 14. Table 14

As for the light-sensitive materials (samples 601A to 604A) which did not contain a developing agent, the samples immediately after coating and the samples after the accelerated storage test were exposed as described above and then processed using a conventional processing bath containing a developing agent (Color Negative Film Processing Agent CN-16) at 38ºC for 165 seconds.

The results are shown in Table 15. Table 15

From the results of Table 14, it is apparent that higher sensitivity and stability can be obtained and that the increase of fog with time can be inhibited particularly in the case of silver halide color photographic light-sensitive material (Sample 604) in which a silver halide light-sensitive emulsion composed of tabular grains containing a metal ion and/or a metal complex ion each being a shallow electron trap in combination with a metal ion and/or a metal complex ion each being a deep electron trap is used and in which a development process is carried out by means of a developing agent contained in the light-sensitive material.

From the results of Table 15, it is apparent that the light-sensitive materials (Samples 601A to 604A) containing no developing agent generally show inferior results compared with light-sensitive materials containing the developing agent. Although fogging during storage of Sample 604A is reduced due to the effect of the silver halide light-sensitive emulsion of the present invention, Sample 604A in particular cannot give the dramatic and excellent effect of the silver halide color photographic light-sensitive material (Sample 604) containing the developing agent.

As in the case of Samples 601A to 604A, the light-sensitive silver halide color photographic materials (Samples 601 to 604) containing the developing agent That is, the samples immediately after coating and the samples after the accelerated storage test were exposed as described above and then processed at 38ºC for 165 seconds using a conventional processing bath containing a developing agent (processing agent CN-16 for color negative film).

The results of the above-described bath process were approximately the same as those of heat development of the silver halide color photographic light-sensitive material containing the developing agent, except that the bath process gave an absolute value of ΔDmin which was about 2/3 lower than in the case of heat development. The change in sensitivity after the above-mentioned accelerated storage of Samples 601 to 604 and Samples 601A to 604A were not significant.

As mentioned above, the sole use of a metal ion and/or a metal complex ion, each of which is a shallow electron trap, results in the increase of Dmin after accelerated storage despite the increase in sensitivity (see Sample 603). On the other hand, the sole use of a metal ion and/or a metal complex ion, each of which is a deep electron trap, inhibits the increase of Dmin after accelerated storage, but high sensitivity cannot be obtained (see Sample 602). However, it is apparent from the results (Sample 604) that the increases in Dmin due to the developing agent contained in the light-sensitive material after the accelerated storage can be effectively prevented by the light-sensitive silver halide emulsion in which the light-sensitive silver halide emulsion is composed of tabular grains containing a metal ion and/or a metal complex ion, each of which is a shallow electron trap, in combination with a metal ion and/or a metal complex ion, each of which is a relatively deep electron trap.

EXAMPLE 8

A method for preparing an ultrafine silver chloride emulsion 4-(a) for epitaxial bonding is described below. To a sufficiently stirred aqueous gelatin solution having the composition shown in Table 6 and a pH of 4, liquid (I) and liquid (II) of Table 7 were added simultaneously in 3 minutes, and 5 minutes thereafter, liquid (III) and liquid (IV) of Table 7 were added simultaneously in 5 minutes.

The reaction mixture was flocculated, washed with water and desalted in a conventional manner (using a flocculating agent (1) and pH 3, adjusted with sulfuric acid). Then, 22 g of lime-treated gelatin was added to the product, which was adjusted to pH 6.1 and pAg 7.1. After adjustment, phenoxyethanol was added. The ultrafine silver chloride emulsion 4-(a) for epitaxial junction thus obtained was composed of cubic grains with an average side length of 0.06 µm. The yield was 635 g.

(Preparation of a silver iodobromide emulsion 2-F (a comparative emulsion) composed of tabular grains with an epitaxial junction)

The procedure for tabular silver iodobromide emulsion 1-E was repeated except that 10 minutes after the addition of sensitizing dyes for chemical sensitization, 35 g of ultrafine silver halide emulsion 4-(a) for epitaxial bonding was added to the emulsion. Then, to the resulting tabular grain silver iodobromide emulsion, chloroauric acid, sodium thiosulfate and selenium sensitizer were added in appropriately adjusted amounts so that the sensitivity of the resulting tabular grain silver iodobromide emulsion was maximum at an exposure of 11100 seconds.

(Preparation of silver iodobromide emulsion 2-G (a light-sensitive silver halide emulsion to be used in the present invention) composed of tabular grains having an epitaxial junction)

The procedure for tabular silver iodobromide emulsion 1-H was repeated except that 10 minutes after the addition of sensitizing dyes for chemical sensitization, 35 g of ultrafine silver halide emulsion 4-(a) for epitaxial bonding was added to the emulsion. Then, to the resulting tabular grain silver iodobromide emulsion, chloroauric acid, sodium thiosulfate and selenium sensitizer were added in appropriately adjusted amounts so that the sensitivity of the resulting tabular silver iodobromide emulsion was maximum at an exposure of 1/100 second.

(Preparation of silver iodobromide emulsion 2-H (a light-sensitive silver halide emulsion to be used in the present invention) composed of tabular grains having an epitaxial junction)

The procedure for tabular silver iodobromide emulsion 1-G was repeated except that 10 minutes after the addition of sensitizing dyes for chemical sensitization, 35 g of ultrafine silver halide emulsion 4-(b) for epitaxial bonding, identical to ultrafine silver halide emulsion 4-(a) for epitaxial bonding except that ultrafine silver halide emulsion 4-(b) for epitaxial bonding contained tripotassium iridium hexachloride in an amount of 3.92 x 10-7 mol in terms of iridium per mol of silver, was added to the emulsion. Then, to the resulting tabular grain silver iodobromide emulsion were added chloroauric acid, sodium thiosulfate and selenium sensitizer in appropriately adjusted amounts so that the sensitivity of the resulting tabular grain silver iodobromide emulsion was maximum at an exposure of 1/100 second.

(Preparation of silver iodobromide emulsion 2-I (a light-sensitive silver halide emulsion to be used in the present invention) composed of tabular grains having epitaxial bonding)

The procedure for the tabular silver iodobromide emulsion 1-F was repeated except that 10 minutes after the addition of sensitizing dyes for chemical sensitization, 35 g of the ultrafine silver halide emulsion 4-(c) for epitaxial bonding, identical to the ultrafine silver halide emulsion 4-(a) for epitaxial bonding except that the ultrafine silver halide emulsion 4-(c) for epitaxial bonding contained potassium ferrocyanide in an amount of 1.5 x 10-3 mol, in terms of iron, per mol of silver, was added to the emulsion. Then, to the resulting tabular grain silver iodobromide emulsion, chloroauric acid, sodium thiosulfate and selenium sensitizer were added in appropriately adjusted amounts so that the sensitivity of the resulting tabular grain silver iodobromide emulsion was maximum at an exposure of 1/100 second.

(Preparation of silver iodobromide emulsion 2-J (a light-sensitive silver halide emulsion to be used in the present invention) composed of tabular grains having epitaxial bonding)

The procedure for tabular silver iodobromide emulsion 1-E was repeated except that 10 minutes after the addition of sensitizing dyes for chemical sensitization, 35 g of ultrafine silver halide emulsion 4-(d) for epitaxial bonding, identical to ultrafine silver halide emulsion 4-(a) for epitaxial bonding except that ultrafine silver halide emulsion 4-(d) for epitaxial bonding contained potassium ferrocyanide in an amount of 1.5 x 10-3 mol, in terms of iron, per mol of silver and tripotassium iridium hexachloride in an amount of 3.92 x 107 mol, in terms of iridium, per mol of silver, was added to the emulsion. Then, to the resulting tabular grain silver iodobromide emulsion were added chloroauric acid, sodium thiosulfate and selenium sensitizer in appropriately adjusted amounts so that the sensitivity of the resulting tabular grain silver iodobromide emulsion was maximum at an exposure of 1/100 second.

Emulsions 2-F to 2-J were composed of grains each having a configuration in which a hexagonal tabular grain had fine grains bonded to its corners by an epitaxial bond. The average aspect ratio and average spherical equivalent diameter of each of Emulsions 2-F to 2-J were approximately the same as those of Emulsion 1-E.

The procedure for preparing Sample 601 in Example 7 was repeated except that the emulsion used therein was replaced with Emulsions 2-F to 2-J in Example 7, and as a result, Samples 701 to 705 were prepared.

The samples were processed, exposed and heat developed as in Example 7. The results are shown in Table 16. Table 16

From the results of Table 16, it is apparent that higher sensitivity and stability can be obtained even in epitaxial tabular grains, and that the increase of fog with time can be prevented particularly in the case of the silver halide color photographic light-sensitive material of the present invention in which a silver halide light-sensitive emulsion containing a developing agent is used and which is composed of tabular grains containing a metal ion and/or a metal complex ion each of which is a shallow electron trap in combination with a metal ion and/or a metal complex ion each of which is a relatively deep electron trap.

EXAMPLE 9 (Preparation of a tabular grain silver chlorobromide emulsion 3-G (a comparative emulsion))

1200 ml of an aqueous gelatin solution having a pH of 4.3, containing 25 g of alkali-treated ossein gelatin dissolved in deionized water and having a methionine content of about 40 µmol/g, 1 g of sodium chloride and 4.5 ml of 1N nitric acid were placed in a reactor, and thereafter the temperature of the solution was raised to 40°C. To this solution, which was vigorously stirred, were then added 36 ml of an aqueous solution (A) containing 20 g of silver nitrate per 100 ml and 36 ml of an aqueous solution (B) containing 0.71 g of potassium bromide and 6.67 g of sodium chloride per 100 ml simultaneously over a period of 45 seconds. After the addition was complete, the reaction mixture was stirred for 3 minutes and simultaneously 43.4 ml of an aqueous solution (C) containing 1.1 g of potassium bromide per 100 ml and 43.4 ml of the solution (A) were added over a period of 30 seconds. After the addition was complete the temperature of the reaction mixture was lowered to 30°C in 3 minutes, and the reaction mixture was kept at that temperature. Then, 108 ml of the aqueous solution (A) and 108 ml of an aqueous solution (D) containing 7.02 g of sodium chloride per 100 ml were simultaneously added to the reaction mixture over a period of 2 minutes and 15 seconds. After the addition was complete, the reaction mixture was stirred for 1 minute, and 20 ml of a 10% aqueous sodium chloride solution and 7 ml of a 1N aqueous sodium hydroxide solution were added so that the reaction mixture had a pH of 6.5 and a silver potential of 80 mV versus a saturated calomel electrode. Thereafter, 2 ml of a hydrogen peroxide solution (35%) was added to the reaction mixture. The temperature of the reaction mixture was then raised to 75°C, and the reaction mixture was allowed to mature at 75°C for 5 minutes.

Then, to the reaction mixture, 1086 g of an ultrafine silver chlorobromide emulsion 5-(a) for epitaxial bonding, identical to the ultrafine silver chloride emulsion 4-(a) for epitaxial bonding except that the ultrafine silver chlorobromide emulsion 5-(a) for epitaxial bonding had a silver bromide content of 5 mol%, was added over a period of 45 minutes while maintaining the silver potential of the reaction mixture at 140 mV. The temperature was then lowered to 35°C and desalting was carried out in a conventional manner.

Thus, a tabular grain silver chlorobromide emulsion 3-G was obtained, which was composed of tabular (100) silver chlorobromide grains having an average grain size of 0.92 µm in terms of average spherical equivalent diameter, an average grain thickness of 0.128 µm, an average aspect ratio of 15.9 and a silver bromide content of 5 mol%.

Chemical sensitization of the tabular grain silver chlorobromide emulsion 3-G was carried out as in the case of the tabular grain silver iodobromide emulsion 1-E except that KI in an amount of 10⁻³ mol per mol of silver and a degradation product of ribonucleic acid were added to the emulsion after the addition of the sensitizing dyes.

The following tabular grain silver chlorobromide emulsions 3-H to 3-J were prepared in the same manner as in the case of the tabular grain silver chlorobromide emulsion 3-G, except as described below. The average grain aspect ratio and the average spherical equivalent diameter of each of the obtained tabular grain silver chlorobromide emulsions 3-H to 3-J were the same as those of the tabular grain silver chlorobromide emulsion 1-E.

(Tabular grain silver chlorobromide emulsion 3-H (a light-sensitive silver halide emulsion to be used in the present invention))

The procedure for preparing tabular grain silver chlorobromide emulsion 3-G was repeated except that an ultrafine silver chlorobromide emulsion 5-(b), identical to emulsion 5-(a) except that emulsion 5-(b) contained tripotassium iridium hexachloride in an amount of 4 x 10-8 mol in terms of iridium per mol of silver, and potassium ferrocyanide in an amount of 2 x 10-4 mol in terms of iron per mol of silver, was added to the emulsion. The thus obtained emulsion 3-H was subjected to the same chemical sensitization as that for emulsion 3-G.

(Tabular grain epitaxial silver chlorobromide emulsion 3-1 (a comparative emulsion))

The procedure for emulsion 3-G was repeated except that 10 minutes after the addition of sensitizing dyes for chemical sensitization, no KI was added, but 35 g of an emulsion 5-(c), identical to emulsion

4-(a) except that the emulsion 5-(c) had a silver bromide content of 100 mol% were added to the emulsion. Then, chloroauric acid, sodium thiosulfate and a selenium sensitizer were added to the resulting emulsion.

(Tabular grain epitaxial silver chlorobromide emulsion 3-J (a light-sensitive silver halide emulsion to be used in the present invention))

The procedure for preparing Emulsion 3-G was repeated except that an Emulsion 5-(d), identical to Emulsion 5-(a) except that the Emulsion 5-(d) containing potassium ferrocyanide in an amount of 2 x 10-4 mol in terms of iron per mol of silver was added to the emulsion. Then, the chemical sensitization procedure of the tabular grain epitaxial silver chlorobromide emulsion 3-I was repeated and Emulsion 3-J was obtained except that 35 g of an Emulsion 5-(e) identical to Emulsion 5-(c) except that Emulsion 5-(e) contained tripotassium iridium hexabromide in an amount of 1.3 x 10-6 mol in terms of iridium per mol of silver was added to the emulsion.

Emulsions 3-I and 3-J were composed of grains each having a configuration in which a rectangular tabular grain had fine grains bonded to its corners by an epitaxial junction.

The procedure for preparing Sample 601 in Example 7 was repeated except that the emulsion used therein was replaced with Emulsions 3-6 to 3-J and as a result, Samples 801 to 804 were prepared.

Samples 801 to 804 were processed, exposed and subjected to heat development in the same manner as in Example 7 except that the heat development was carried out at 75°C for 10 seconds. The results are shown in Table 17. In Table 17, the sensitivities are given as relative values, taking the sensitivity of Sample 801 as 100. Table 17

In comparison with the results of Sample 601 in Example 7, it is also apparent from the results of Table 17 that the fogging due to the developer contained increases during storage of the light-sensitive material, and that the increase in fogging during storage is more significant in the emulsion with a high silver chloride content due to its higher activity than in the Silver iodobromide emulsions. However, it is apparent from the results that even in an emulsion having a high silver chloride content, the increase in Dmin due to the developing agent contained can be very effectively inhibited while maintaining high sensitivity in the case of the silver halide color photographic light-sensitive material having a high silver chloride content in which a silver halide light-sensitive emulsion containing a developing agent is used and which is composed of tabular grains containing a metal ion and/or a metal complex ion each of which is a shallow electron trap in combination with a metal ion and/or a metal complex ion each of which is a relatively deep electron trap. It is apparent that the above-mentioned effect is also significant in an emulsion composed of epitaxial tabular grains having a high silver chloride content.

Example 10 (Tabular grain silver iodobromide emulsion 4-E (a comparison emulsion))

The pH of 1000 ml of an aqueous solution containing 0.5 g of oxidation-treated gelatin and 0.37 g of KBr was adjusted to 2 by adding H₂SO₄, and the reaction mixture was stirred at 40°C. To the reaction mixture were simultaneously added 50 ml of a 0.3 M AgNO₃ aqueous solution (A) and 50 ml of a 0.3 M KBr aqueous solution (B) in 40 seconds by double jet. After the pH of the reaction mixture was adjusted to 5.0 by adding NaOH, the temperature of the reaction mixture was then raised to 75°C in 35 minutes. After adding 35 g of oxidation-treated gelatin, 505 ml of a 1.2 M AgNO3 aqueous solution (C) and 437 ml of a 1.4 M KBr aqueous solution (D) were added at this temperature in 33 minutes by accelerating the flow rate (the final flow rate was 5.2 times the initial flow rate) while maintaining the pAg at 8.58. The reaction mixture was cooled to 55 °C, and 104 ml of a 0.4 M AgNO3 aqueous solution (E) and 279 ml of a 0.12 M KBr aqueous solution (F) were added to the reaction mixture in 5 minutes at a constant flow rate. After adjusting the pAg to 8.8 by adding an aqueous KBr solution, 110 ml of an aqueous 1.8 M AgNO3 solution (G) and 125 ml of 1.8 M KBr aqueous solution (H) were added to the reaction mixture to prepare an emulsion.

The temperature of the emulsion was then lowered to 35ºC and thereafter the emulsion was flocculated in a conventional manner. After a water wash step, 75 g of gelatin was added to the flocculated product which was adjusted to pH 5.5 and pAg 8.2.

In this way, an emulsion was obtained in which the projected area of tabular grains exceeded 99% of the total projected area of all the grains, and the tabular grains had an average spherical equivalent diameter of 0.50 µm, an average grain thickness of 0.07 µm, an average aspect ratio of 15 and an average circular equivalent diameter of 1.09 µm.

(Tabular grain silver iodobromide emulsion 4-F (a silver halide emulsion to be used in the present invention))

The procedure for preparing the tabular grain silver chlorobromide emulsion 4-E was repeated except that the solution (D) contained tripotassium iridium hexachloride in an amount of 3.5 x 10-8 mol in terms of iridium and the solution (H) contained potassium ferrocyanide in an amount of 8 x 10-5 mol in terms of iron. The average grain aspect ratio and the average spherical equivalent diameter of the obtained emulsion were approximately equal to those of the emulsion 4-E.

(Tabular grain silver chlorobromide emulsion 4-G (a comparison emulsion))

A mixture of 12.5 g of gelatin with an average molecular weight of 15,000, 4.35 g of potassium bromide, 0.32 g of potassium chloride and 950 ml of distilled water was placed in a reactor, and then the temperature of the mixture was raised to 45°C. To this solution, which was vigorously stirred, were then added 50 ml of an aqueous solution (A) containing 8.3 g of silver nitrate and 50 ml of an aqueous solution (B) containing 2.67 g of potassium bromide over a period of 45 seconds. The temperature of the mixture was kept at 45°C for 4 minutes, and then the temperature of the reaction mixture was raised to 63°C. Then 17.0 g of gelatin were added together with 130 ml of distilled water was added to the reaction mixture. Thereafter, 150 ml of an aqueous solution (C) containing 51.2 g of silver nitrate and a 24.80% aqueous solution (D) of potassium bromide were added to the reaction mixture over a period of 13 minutes in such a manner that the flow rate of addition gradually increased and that the silver potential of the reaction mixture was 0 mV against a saturated calomel electrode. After the addition was complete, the temperature of the mixture was maintained at 63 °C for 2 minutes, and then the temperature of the reaction mixture was lowered to 45 °C. Then, 50 ml of an aqueous solution (E) containing 5.9 g of silver nitrate and 320 ml of an aqueous solution (F) containing 5.82 g of potassium iodide were added to the reaction mixture over a period of 5 minutes. Thereafter, 350 ml of an aqueous solution (G) containing 104.3 g of silver nitrate and a 25% aqueous solution (H) of potassium bromide were added over a period of 45 minutes to the reaction mixture in such a manner that the silver potential of the reaction mixture was 10 mV against a saturated calomel electrode. After the addition was complete, 1.4 g of potassium bromide and 4 mg of sodium ethylsulfonate were added to the solution, and the temperature of the solution was kept at 45 °C for 5 minutes. Then, the temperature of the solution was lowered, and desalting was carried out by a conventional method.

In this way, an emulsion composed of hexagonal tabular grains with an average spherical equivalent diameter of 0.37 µm, an average circular equivalent diameter of 0.18 µm and an average aspect ratio of 5.8 was obtained.

(Tabular grain silver iodobromide emulsion 4-H (a light-sensitive silver halide emulsion to be used in the present invention))

The procedure for preparing the tabular grain silver iodobromide emulsion 4-E was repeated except that the solution (D) contained tripotassium iridium hexachloride in an amount of 3.5 x 10-8 mol in terms of iridium and the solution (H) contained potassium ferrocyanide in an amount of 8 x 10-5 mol in terms of iron. The average grain aspect ratio and the average spherical equivalent diameter of the obtained emulsion were approximately equal to those of the emulsion 4-G.

Chemical sensitization of these emulsions was carried out in the same way as for the comparative emulsion 1-E. That is, chloroauric acid, sodium thiosulfate and a selenium sensitizer were added to the emulsions in appropriately adjusted amounts so that the sensitivity of the emulsions was maximum at an exposure of 1/100 second. The amounts of the dyes for spectral sensitization and the chemical sensitization stoppers were adjusted proportionally depending on the surface area of the emulsion grains.

The sensitization procedures for both the comparative tabular grain silver iodobromide emulsions 1-E, 4-E and 4-G and the tabular grain silver iodobromide emulsions for the present invention 1-H, 4-F and 4-H were repeated, except that the sensitizing dyes were changed to sensitizing dyes (a mixture of sensitizing dyes V to VII for red-sensitive emulsions) for red-sensitive emulsions, and thus emulsions 1-E(r), 4-E(r), 4-G(r), 1-H(r), 4-F(r) and 4-H(r) were prepared. Meanwhile, both the sensitization procedures for the comparative tabular grain silver iodobromide emulsions 1-E, 4-E and 4-G and the tabular grain silver iodobromide emulsions for the present invention 1-H, 4-F and 4-H were repeated except that the sensitizing dyes were changed to a sensitizing dye (a sensitizing dye IV for blue-sensitive emulsions) for blue-sensitive emulsions, and thus 1-E(b), 4-E(b), 4-G(b), 1-H(b), 4-F(b) and 4-H(b) were prepared.

A multilayer photosensitive material (sample 901) was prepared which had the same constitution as that shown in Tables 10 to 12, except that emulsions 1-E, 4-E and 4-G were used for a high sensitivity layer, a medium sensitivity layer and a low sensitivity layer in a green sensitive magenta coloring layer; emulsions 1-E(r), 4-E(r) and 4-G(r) were used for a high sensitivity layer, a medium sensitivity layer and a low sensitivity layer in a red sensitive cyan coloring layer; and emulsions 1-E(b), 4-E(b) and 4-G(b) were used for a high sensitivity layer, a medium sensitivity layer and a low sensitivity layer in a blue sensitive, yellow coloring layer.

A silver halide multicolor color photographic light-sensitive material (Sample 902) of the present invention was prepared by repeating the procedure for Sample 901 except that the emulsions used therein were changed as shown below in Sample 901. That is, in the formulation of Sample 901, emulsions 1-E, 4-E and 4-G were changed to emulsions 1-H, 4-F and 4-H, and emulsions 1-H, 4-F and 4-H were used for a high sensitivity layer, a medium sensitivity layer and a low sensitivity layer in a green sensitive magenta coloring layer; emulsions 1-H(r), 1-F(r) and 4-H(r) were used for a high sensitivity layer; a medium-sensitivity layer and a low-sensitivity layer were used in a red-sensitive, cyan-dyeing layer; and the emulsions 1-H(b), 4-F(b) and 4-H(b) were used for a high-sensitivity layer, a medium-sensitivity layer and a low-sensitivity layer were used in a blue-sensitive, yellow-dyeing layer.

Meanwhile, according to the method for preparing dispersions of couplers as shown in Example 7, a cyan coupler dispersion and a yellow coupler dispersion were prepared. In addition, in order to prepare a color layer capable of losing color in a heat development process, a coloring dispersion was also prepared by using a combination of the yellow, magenta and cyan leuco dyes with a zinc complex.

The photographic characteristics of Sample 902 were examined in the same manner as in Example 7, except that the filter was removed at the time of exposure.

Sample 902 was exposed to light of 1000 lux 1/100 second via an optical wedge. After exposure, heat development was carried out by the method comprising supplying 20 ml/m² of warm water of 40ºC to the photosensitive layer of Sample 902, bonding the photosensitive layer and the processing layer of the first processing material P-3, front side on front side, and then heating the materials to 83°C to keep them at that temperature for 30 seconds using a heat drum. Then, the sample 902 was removed from the processing material P-3, and the sample 902 was subjected to a second processing using a second processing material P-2. The second processing was carried out by the method comprising supplying 15 ml/m² of water to the processing layer of the second processing material P-2, joining the processing layer and the photosensitive layer of sample 902 which had been subjected to the first processing, front side to front side, and thereafter heating the materials to 60°C to keep them at that temperature for 30 seconds using a heat drum. The image of Sample 902 after the above-described processing was subjected to transmission density measurement of yellow, magenta and cyan wedge images using blue, green and red filters to obtain a so-called characteristic curve. Incidentally, the processing material P-3 was the same as the processing material P-1 in Example 7 except that the amount of guanidine picolinate was changed to 4500 mg/m.

As in Example 7, the sensitivity was expressed by a relative value obtained by taking the reciprocal of the exposure amount corresponding to a density higher than the fog density by 0.15 and setting the sensitivity of Sample 901 as 100. The sensitivities of Sample 902 were expressed as a relative value based on the sensitivities of Sample 901. The results are shown in Table 18. Table 18

As is clear from Table 18, the effect of the present invention, characterized by a high sensitivity and a very small increase in Dmin after accelerated storage, is also observed in a multilayer silver halide multicolor color photographic light-sensitive material (Sample 902) as in Example 7.

EXAMPLE 11

A multilayer photosensitive material 1001 was prepared by repeating the procedure for Sample 901 except that a medium sensitivity layer and a low sensitivity layer as used therein were removed from the blue-sensitive yellow coloring layer, the green-sensitive magenta coloring layer and the red-sensitive cyan coloring layer; Emulsion 3-G was used for the high sensitivity layer of the green-sensitive magenta coloring layer; Emulsion 3-G(r), identical to Emulsion 3-G except that a sensitizing dye for a red-sensitive emulsion was used in Emulsion 3-G(r), was used for the high sensitivity layer of the red-sensitive cyan coloring layer; and Emulsion 3-G(b), identical to Emulsion 3-G except that a sensitizing dye for a blue-sensitive emulsion was used in Emulsion 3-G(b), was used for the high-sensitivity layer of the blue-sensitive yellow-coloring layer.

Next, a silver halide color photographic light-sensitive material (Sample 1002) was prepared as in Example 9 except that use was made of Emulsion 3-J(r), identical to Emulsion 3-J except that a sensitizing dye for a red-sensitive emulsion was used in Emulsion 3-J(r), Emulsion 3-J(b), identical to Emulsion 3-J except that a sensitizing dye for a blue-sensitive emulsion was used in Emulsion 3-J(b), and Emulsion 3-J.

Sample 1002 was processed as in Example 10 except that the second process carried out therein was omitted and the heat development condition of the first process was 17 seconds at 80ºC. As a result, the Effect of the present invention characterized by a high sensitivity and a very small decrease in Dmin after the above-mentioned accelerated storage as observed in Example 10.

Since the sample 1002 forms little fog even if the second processing, which is a fixing step, is not performed, the sample 1002 is suitable for easy and quick use because the image information does not deteriorate when the image information is read by a scanner.

EXAMPLE 12

Sample 902, which had a multilayer structure prepared in Example 10 and a support which was the same as that prepared in Example 6 except that resorcinol was omitted from the antistatic layer of the support (transparent PET base) of Example 6, was loaded into a cartridge. When the sample was examined in the same manner as in Example 10, the sample was excellent as in the case of Sample 902, thereby confirming the effect of the present invention which is characterized by high sensitivity and the enhancement of stability in a photosensitive material system containing a developing agent by using a combination of a metal ion and/or a metal complex ion which are a shallow electron trap and a metal ion and/or a metal complex ion which are a relatively deep electron trap.

Claims (9)

1. A light-sensitive, color photographic silver halide material with a support with a photographic build-up layer applied thereon, which contains at least a light-sensitive layer which comprises a light-sensitive silver halide emulsion, a developing agent, a compound capable of forming a dye by a coupling reaction with the oxidation product of the developing agent and a binder, wherein the photosensitive, color photographic silver halide material is, after exposure, combined with a processing material comprising a support having applied thereto a build-up layer containing a processing layer comprising a base and/or a base precursor, in the presence of water which is added to the photosensitive layer of the photosensitive, color photographic silver halide material or to the processing layer of the processing material in an amount in the range of 1/10 to the equivalent of an amount required for maximum swelling of the total applied layers of these materials, so that the photosensitive layer and the processing layer are opposite each other, and heated for heat development to produce a color image in the photosensitive, color photographic silver halide material, wherein the light-sensitive silver halide emulsion contains at least one ion selected from the group consisting of a metal ion and a metal complex ion each having an electron trap depth of 0.6 eV or less, and at least one kind of tabular grains having an average aspect ratio of 4 to 100, provided that the at least one ion contained in the light-sensitive silver halide emulsion is not a metal ion or a metal complex ion derived from potassium hexachloroiridate, and provided that the light-sensitive silver halide emulsion is not an emulsion comprising tabular (111) silver chlorobromide grains containing 5 mol% of silver bromide and a metal ion or a metal complex ion derived from yellow prussiate. 2. The silver halide color photographic light-sensitive material according to claim 1, wherein the metal ion or the metal complex ion has an electron trap depth of 0.4 eV or less. 3. The silver halide color photographic light-sensitive material according to claim 1, wherein the metal ion or the metal complex ion has an electron trap depth of 0.2 eV or less. 4. The silver halide color photographic light-sensitive material according to claim 3, wherein the metal ion and the metal complex ion having an electron trap depth of 0.2 eV or less are selected from the group consisting of Pb²⁺ and [M(CN)xLyNz], respectively, wherein M is selected from the group consisting of Re⁺, Os²⁺, Ru²⁺, Fe²⁺, Ir³⁺ and Co³⁺, x is an integer of 4 to 6, L and N are selected from the group consisting of halide ions, SCH⁻, NCS⁻, H₂O, pyridine, phenanthroline, imidazole and pyrazole, and y and z are numbers determined so as to satisfy the equation x + y + z = 6. 5. The light-sensitive silver halide color photographic material according to any one of claims 1 to 4, wherein the developing agent is represented by one of the following general formulas I to IV: General Formula I General Formula II General Formula III General Formula IV wherein R₁ to R₄ each represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group, an alkylcarbonamide group, an arylcarbonamide group, an alkylsulfonamide group, an arylsulfonamide group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an alkylcarbamoyl group, an arylcarbamoyl group, a carbamoyl group, an alkylsulfamoyl group, an arylsulfamoyl group, a sulfamoyl group, a cyano group, an alkylsulfonyl group, an arylsulfonyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkylcarbonyl group, an arylcarbonyl group or an acyloxy group; R₅ represents an alkyl group, an aryl group or a heterocyclic group; Z represents a group of atoms forming a heterocyclic or aromatic ring and having the sum of the Hammett constants σ. of the substituents is 1 or more if Z represents a group of atoms forming a benzene ring; R₆ represents an alkyl group; X represents an oxygen atom, a sulfur atom, a selenium atom or an alkyl or R₇ represents a tertiary nitrogen atom bearing an aryl substituent; R₇ or R₈ represents a hydrogen atom or a substituent; R₇ and R₈ may be linked to form a double bond or a ring; and each of the compounds represented by the general formulae I to IV contains at least one ballast group having 8 or more carbon atoms to impart oil solubility to the molecule. 6. The silver halide color photographic light-sensitive material according to any one of claims 1 to 5, wherein the silver halide light-sensitive emulsion contains at least one ion selected from the group consisting of a metal ion and a metal complex ion each having an electron trap depth of 0.2 eV or less, together with at least one ion selected from the group consisting of a metal ion and a metal complex ion each having an electron trap depth of 0.35 eV or more. 7. The silver halide color photographic light-sensitive material according to claim 6, wherein the metal ion and the complex ion having an electron trap depth of 0.2 eV or less are selected from the group consisting of Pb²⁺ and [M(CN)xLyNz], wherein M is selected from the group consisting of Re⁺, Os²⁺, Ru²⁺, Fe²⁺, Ir³⁺. and Co³⁺, x is an integer from 4 to 6, L and N are selected from the group consisting of halide ions, SCH, NCS, H₂O, pyridine, phenanthroline, imidazole and pyrazole, and y and z are numbers determined to satisfy the equation x + y + z = 6), and the metal ion or the metal complex ion having an electron trap depth of 0.35 eV or more are selected from the group consisting of an ion containing a halide ion ligand or a thiocyanate ion ligand and an element selected from the group consisting of Ir, Rh, Ru and Pd, an ion containing at least one nitrosyl ligand and Ru, and an ion containing a cyano ligand and Cr. 8. A method for producing a color image, comprising the steps of: combining a light-sensitive silver halide color photographic material after its exposure and a processing material having a having coated thereon a make-up layer containing a processing layer comprising a base and/or a base precursor, in the presence of water supplied to the light-sensitive layer of the silver halide color photographic light-sensitive material or to the processing layer of the processing material in an amount in the range of 1/10 to the equivalent of an amount required for maximum swelling of the entire coated layers of these materials so that the light-sensitive layer of the silver halide color photographic light-sensitive material and the processing layer are opposed to each other, and heating these materials for heat development to form a color image in the silver halide color photographic light-sensitive material, wherein the silver halide color photographic light-sensitive material is the silver halide color photographic light-sensitive material according to any one of claims 1 to 7. 9. The method for forming a color image according to claim 8, wherein the heat development is carried out at a temperature of 60°C to 150°C.